FAQs about Metal Halide & Halogen Lights and Lighting for Marine Systems 4 Related FAQs: Metal Halides 1, Metal Halides 2, Metal Halides 3, Metal Halides 5, Metal Halides 6, Metal Halides 7, Metal Halides for Small Systems, Metal Halides for 40-200 gal. Systems, MH for 200 gal. Plus Systems, Metal Halide Lamp Issues, Metal Halide Fixture Issues, Metal Halide Heat Issues, MH Repair Issues, Compact Fluorescents, Regular Fluorescents, Lighting Marine Invertebrates, LR Lighting,  Tridacnid Lighting, Small System Lighting, Related Articles: Metal Halide Light, & Lighting Articles, Coral System Lighting, Match your fixture to your lamp/s to your ballasting... or risk fire...

Going For Glitter Lines! (Metal Halide Lighting) Hi, <Hi there! Scott F. here today> I currently have 4-110 watt VHO's over my 55 gallon tank.  I know I have efficient lighting but I would like to have the shimmer effect that MH's provide.  I was wondering if there is any other bulb that will safely produce the same shimmer effect?  If so, what is the best way to install them or the MH's inside a canopy along with the VHO's?  Thanks for your time. Chad <I am not aware of any bulbs that will create the "glitter lines" that metal halides are known for. As far as installing metal halides in a canopy- there are numerous options, ranging from pendants (such as the Sunlight Supply or PFO units) that you simply mount inside your wooden canopy, to "retrofit" units, which include the bulb holders and reflective material. Do some searching among the e-tailers on the 'net, and you'll find a variety of units out there that will do the job. Good luck! Regards, Scott F.>

- Got Shimmer? - Hi, I currently have 4-110 watt VHO's over my 55 gallon tank.  I know I have efficient lighting but I would like to have the shimmer effect that MH's provide.  I was wondering if there is any other bulb that will safely produce the same shimmer effect? <Not that I am aware of.> If so, what is the best way to install them or the MH's inside a canopy along with the VHO's? <Well... typically if you want metal halide lamps in a canopy, you need to make sure it's about eight to ten inches tall. The typical canopy is six inches tall. In any case, metal halide retrofit kits are available and folks typically place them between the fluorescent tubes.> Thanks for your time. Chad <Cheers, J -- >

MH Q's Hello there crew,          Thank you guys for all the valuable info you've given me! <No problem :D>    Once again I'm stumped and need your guys help.  I'm looking to buy a MH lighting system for my 70g tall tank (36x18x24) with a 5-6" sand bed.  I'm looking to keep clams and SPS corals along with a Heteractis Magnifica (beautiful but demanding I know).   <Very demanding, and best kept on its own in a species tank.  These anemones can get to be a meter across, and will feel a bit cramped in your 18" wide tank!>   I've more or less decided on dual 250w 10k Ushios <I'd go with 400W for this anemone if you decide to get it-- it needs a LOT of light.  If you stick with just SPS/Clams 250 should be okay.> but can't discern what is the big difference between the regular socket type bulbs and double ended HQI bulbs.   <In general HQIs put out more light per wattage>   Either way both will run off the appropriate dual PFO ballast.  Both of  them will have reflectors and a glass cover also.  My big question is are either of them more powerful than the other?  I've read that HQI's can have higher PAR values than regular bulbs.  I've also heard they have a bluer output than traditional bulbs of the same wattage and cooler temp.  They also require a digital ballast from what I've come to understand also.  That explains the higher cost of the HQI ballast I suppose.  I like the 10k color spectrum when used alone and just need to know some of the Pros and Cons of the two formats (HQI vs. Standard). <Well for SPS corals just about any of the commonly sold bulbs will grow them just fine.  If you're looking to farm them or something I'd go with a combo of 10000K and 20000K OR 6500K and 20000K.  This is what Steve Tyree has suggested in the past.  But it really comes down to your color preference when choosing what Kelvin you get...>                            Sincerely,   Chris  AKA  ~ fishtank ~ MH (DE)pendant glass shield Hi crews, It's been sometimes again that I didn't write in. I have been asking around in the forum but I guess I need the assurance from WWF crews. I just went cheap recently and get a used 150W DE MH pendant. Although equipped with a 10000K BLV bulb, one thing weird is its glass shield is the frosted type and not the clear type. Will this shield cuts down a lot of light or it just polarizes the light? Or this is just good for photo acclimation? Can you give a ballpark figure on the percentage of PAR being blocked or polarized? How likely is it to crack if I change it to untempered glass? And I've also been pondering whether to put it 6" or 12" above tank. Thanks a lot. Wid >>That is odd. I would contact the people who made the fixture - it should not have frosted glass, it should be clear. Frosted will cut down on PAR, but I couldn't give you a percentage because it could be anything! >>IIRC untempered would be fine,3/16", but I would go to a glass shop and check price difference. >>The distance from the water is really up to you. It is nice to make it adjustable so you can acclimate new corals to your lights. >>Rich Re: MH (DE)pendant glass shield Hi Rich, Thanks for your swift response. Btw just an update. There is no brand on this pendant and I suspect that it is meant for general use and not for aquarium use, although it is fixed with a BLV 10000K. What make me worry most is the reflector might not be the best if my assumption is true. Anyway I ordered a piece of 2mm clear tempered glass shield and hopefully it fit perfect. And I also hope that it is not a probe start ballast. Thanks again. Wid >>No problem! Hope it works out >Rich

Kelvin? hi I was wondering how much Metal halide lighting to have on a reef aquarium in Kelvin ???? thanks >>>Hello, There is no answer to your question as stated. Kelvin is not a measure of HOW MUCH, but of color temperature. 10K and 20K are the more common choices when speaking of such. The higher the rating, the more blue the light is. I've recently become a fan of the 20k HQIs after running the 10k's for years. Jim<<<

Light Temp - again. hi I was wondering what is the best Kelvin to run on a reef aquarium??? Without any fluorescent etc. thanks >>>Hello Dana,    There is no conclusive data pointing to a "best" Kelvin range for a reef tank. Besides, there are deep water critters and shallow water critters which are certainly accustomed to various Kelvin ranges. For the purposes of most reef tanks, anything between 10 and 20K is fine. Jim<<<

Wanting to downgrade lighting Hi Bob, << Blundell today. >> I have a 36"L x 18"W x 30"H tank with 5" DSB. Planning to change my 2 x 250W SE MH lights to something else due to the high electricity consumption and heat contributed by the Metal halides. Would like to find out what other alternatives do I have in order to meet the minimum requirements of a 30" depth with mostly SPS at the top and LPS at the bottom / middle portion of the tank. << I wouldn't down grade your lights.  Pricey as it may be, that sounds like good lighting.  If anything I'd switch to 150 watt double ended but I'd still rather have your two 250 watt. >> p/s: I have attached a photo of my tank, hope it helps. Thanks for your precious time, James <<  Blundell  >>

Ideal halide Kelvin rating? Hi bob, << Blundell here. >> I'm using 2 x 250W 20K BLV now, I love the soothing lightings & colours of the corals shown under it but I notice the PAR might not be strong enough to reach the corals at the tank bottom and also the Acros are not growing as fast. << Yes I have that exact type of lighting and problem.  I really like the 20k look but the amount of visual light given off is just way too low. >> Have tried the 10K before, love the growth and PAR but dislike the bright whiteness of the light and also the corals ain't that colourful when compare with the 20K bulbs. Pls give me your advice. << You asked the right person.  I've been looking into this heavily and have decided (for the time being) that the Aqualine Busch bulbs are probably the best.  But the brand name is only somewhat important, the main key (to looks and growth) I think is probably the new line of 14k's now on the market.  That is what I'm switching to.  However, 10k's with supplemental actinics is really nice as well. >> regards, James <<  Blundell  >>

Metal Halide Thank you very much for the input!  I actually just got my metal halide pendant yesterday (I stuck w/ the 150w 20,000K), and it's wonderful!  I have it placed (as you suggested) around 7" above my tank and actually, to my surprise, almost the entire tank is well lit.  Just the very very ends of the tank are more dim (but not dark), but I don't have any corals placed on the extreme ends anyway. I've been reading thru other forums and folks have been saying that my lights are just barely sufficient for Acro's or other more colorful SPS to survive and thrive, and that I should either 1) add another 150w (but as you also advised, I prefer not to do this) or 2) upgrade to 250w pendant.  Just wanted to get your advice on this as well...(probably since I have an opportunity to buy a blue tort or blue Monti w/in the near future at reasonable price). Secondly, another common notion (and I think more accurate) among some of the forums I frequent is that there is no way I can have maxima clams or other more colorful (i.e. blue) clams in my tank (not including water parameter issues which of course is a huge factor as well) based on my 150w metal halides...I tend to agree, but I am not an expert in clams, so just wanted to get your advice on this as well.  Basically, I have a hard time accepting the idea of pushing any higher w/ metal halide wattage for my system b/c I already have had heat issues in the past and must therefore run my air conditioner a lot in Sunny Southern California.  I do hear reports of folks using even two 150/175watt MH pendants on even 20g alone, yet I have no idea how I could pull that off even w/ my 30g plus 20g refugium/sump.  Any input would be much appreciated!  Thank you very much again! -Dennis >>>Hey Dennis,   Congrats on your new light.  I've used these, I'm very familiar with them, and I STRONGLY  suggest you put it at least 10" above the acrylic. You do not want the acrylic top of your tank over heating. I've seen more than one cracked top from this. The manufacturer suggests a height of 35cm, and there is a good reason for this. Heed the directions. I cannot say this in strong enough terms. DO NOT keep that fixture 7" above the tank! READ THE DIRECTIONS! I hope I've been clear on that issue. :) It might take weeks or months, but the top of your tank WILL crack.   I have to say I agree that you will tend to lose a bit of color on certain SPS corals. If you are frequenting Reefs.org, then most people there (myself included, hehe) know their stuff. If you're frequenting Reef Central, then you have people that know their stuff, but a ton of newbies that hand out advice like they've been keeping these tanks for decades. Beware. Anyway, regarding the corals, nothing is all the time, and you will have to experiment. Montipora digita, encrusting Montis, Monti capricornis, Bali slimers, many Pocillopora and some acros will do just fine. Most blue acros will go brown under your lights. You lose a bit of intensity going with a 20K vs. a 10K, but the color rendition is better. Most of the nicer SPS only tanks I've seen run the 400w radiums. I normally wouldn't run anything less than a 250W DE fixture (which is what I use BTW) on a tank dominated by SPS corals. Euphyllia, (frogspawn, hammer and torch corals) will all do great in your tank. After messing with 150's for a while, I came to the conclusion that 250's are a better investment, especially for SPS and clams. However, given your tank size, I think you made the right choice. Keep in mind though a coral's light requirement does not decrease just because you are keeping it in a smaller tank. A coral that needs 250w of light under 12" of water to maintain color in a 180 gallon tank, still needs 250w under 12" of water to maintain color in a 30 gallon tank. This is a point many people don't seem to understand.   A maxima will do just fine in your tank. I had a maxima under a 150w fixture for a long time, and he grew like a weed. Put him on the rocks, at least halfway up in the tank though. I would steer clear of T. crocea perhaps, but T. maxima, T. derasa, and T. squamosa are possibilities. Regards Jim<<<   Metal halide in Australia 9/21/04 Hi,  How much would a good metal halide bulb cost AU as cheap as possible??  Thanks <I really have no idea.  In the US, the range from about $60 up to about $100 USD.  "industrial grade" lamps can be purchased as cheaply as $15 USD.  Simply figuring the exchange may not account for different shipping rates, tariffs, etc.  Do look for one of the Aussie marine aquarium message boards for more help.  Best Regards.  AdamC.>

Metal Halide question 9/20/04 Hi. I was wondering how many metal halide lights would I need for a 5ft tank depth 70cm, also in AU how much would the cheapest but still good metal halide lamp be????  Thanks <I am not familiar with the market for lamps in Australia, but in the US, metal halide lamp prices are falling.  Prices on good well known lamp brands (Aqualine, Ushio, Iwasaki, radium) have become bargains compared to their prices a few years ago.  This has been driven by competition from a variety of Asian made lamps that are very good and very affordable (look for XM and Coralvue).  The general rule of thumb is to cover each 2 square feet with on metal halide.  Since you have an odd number, I personally would err on the low side and use two lamps (especially since you never want to position a MH lamp over a center brace).  At 70cm of depth, 175w lamps will provide you with enough light for most things if you are happy to keep only lower light animals in the lower 1/3 of the tank. If you wish to keep higher light animals throughout, choose 250W.  Please do avoid "industrial" grade lamps that will have a very poor appearance and less useful spectrum than aquarium lamps.  Instead, save money by shopping non-aquarium sources for ballasts, sockets and build your own!  Best Regards.  Adam>

LIGHTING CHANGE Short and simple, crew.  I currently have 360 watts of Comp  Fluorescents over a 90 gallon.  I am interested in a 2 x 250w, 10,000K  Halides, with 2 x 96w actinics.  Is it too much, would I be better off with  175's? <Simple answer is that it depends on what you want to do with the lights, what animals you wish to keep. MacL> -Splash guards are your friends!- Hi There! <Hellooooo, Kevin here> I recently purchased a 4x96w power compact retrofit kit from PFO lighting and having some difficulties. The kit came with 2 96w actinics and 2 96w 1000K bulbs from Hamilton tech. <Hah, go figure PFO is selling Hamilton's lamps...> I placed the bulbs about 2 inches above an open 40 gal reef tank. <Ooo my, that's a no can do.  Note that the end caps on the lamps are NOT waterproof, the lamp clips and reflector are both metal which will rust in short order without protection. This fixture is not meant to be placed so close to the water! If you plan on keeping it this close, you'll need to devise an acrylic splash guard to protect your investment or your bulbs will continue to pop and your fixture will look like the titanic.> Within 1 week of use, the two 10000K bulbs have cracked/shattered, while the actinics are still working fine. What's going on here? <The cracking/shattering is clearly from water splashing on the hot lamps. It's unlikely that the lamps are defective, but who knows.>Is there something that I should know about these types of lamps that I'm doing wrong?. or is it possible that the lamps are defective? Any insight would be appreciated. Thanks, Marc <Get that thing off of the water or use a splash guard and you'll be all set. Good luck! -Kevin>

LFS Opinions and Publication Truth 9/13/04 (MHs, light, corals) Good morning, guys! <cheers> Please push Ivan away from us here in South Louisiana and push it farther away from Florida! <heehee... if only I could> The last thing they need is more rain! I visited my LFS/LRS, probably the best one in South Louisiana, yesterday. I had intentions of purchasing a 6500?K bulb for a pendant I have, and probably a 175w 10,000K setup for my 58g. They freaked out when I asked for the 6500. <bizarre... I cannot fathom why> Now, every book I've read, new and old, has suggested that lower Kelvin can be advantageous and economically friendly to some corals. <exactly... it is THE best light for a majority of corals> Information gleaned from wetwebmedia.com, the best source, IMHO, suggests the same. The owner, normally a helpful guy, tried to tag team me with a scientific sounding employee into discovering that 6500 is the way of the dinosaurs and I should learn from their mistakes and buy the 20,000K. <wow... not only are they mistaken, but 20kK is actually not helpful for a majority of corals... that is to say - used alone, 20k K will suffer many photosynthetic corals because they lack adequate amounts of daylight in the spectrum to stimulate adequate photosynthesis.> I asked how PAR ratings compare to the "plain-ol'" 6500s and how 20,000 is better, other than just marketing and personal preference. Grunts and mumbles followed. <do a google search for "Sanjay Yoshi" to read some of his studies and results regarding PAR values> The scientific guy said he wouldn't hesitate adding a 400w 20,000K to his nanoreef tank, again going in the face of anything I've read. What's the opinion from anyone over there? <they have caught up in the hype... there is no basis for using heavy blue/20k K only... quite the contrary for garden reef displays> I think Mr. Calfo would have something to say. I would really like the experienced, non-sales driven opinion here. Once again, thanks! Ian <with kind regards, Anthony>

Halide bulb preference I almost forgot to ask what types/brand of metal halide lighting do you use and what P/C Fixtures? bulbs do you recommend? << Right now I'm using a Helios ballast to run my two 150 watt 20k lights. They are 20XM bulbs.  They are awesome color, but they just don't look bright enough to me.  I'm thinking that if I did it again I would either use the AqualineBusch 14K bulbs, or use some sort of 10k with actinic supplements. For the PC or VHO, I don't really have a preference. >> Aaron <<  Blundell  >>

Metal halide over an acrylic tank 9/1/04 Hello WWM crew! <Howdy> I currently have a clear-for-life 30g show(36"Lx12"Wx16"H)set-up with mostly zoanthids, mushrooms, Ricordea, and one candycane/trumpet coral.  There is also a 20g long AGA aquarium under the main display serving as a sump/refugium w/ tons of pods. <very nice> While I currently have 130w PC's for the main display, I recently purchased (but it is on back-order now) one Aqua Medic 150w 20,000K Metal Halide HQI pendant.   <a proper wattage... and the light is rather blue, but still fine as long as you stay with these polyps and deeper LPS corals. Else stray closer to 10k K lamps> I plan to have it approximately 10" above the water level.   <a bit too high... 6-8" would be better most likely. But do check the spread of light once mounted> Will this pendant be sufficient for my set-up (i.e. will it actually reach most of the 36" length of my display tank?  Or should I order another one and have 2 of them hanging above my tank? <Yikes! two would be one too many. One MH is fine here bro> Secondly, as you probably know, the acrylic tank only has 2 rectangular openings at the top of the tank and right now I have an acrylic cover that came w/ the tank over the opening.  Will I need to leave the acrylic cover off for the metal halides?   <nope... not if the MH comes with its own lens, and it almost certainly does> Just worried about evaporation issues.   <inevitable... and its a chance to bring more Kalkwasser in to the system? Will the metal halides damage my acrylic tank due to the heat issues?   <not if its high enough. over six inches should be fine> Thanks in advanced for any input.  I've followed a lot of your advice on your site and my tank has been thriving thus far because of it!  Thanks again! -Dennis <best of luck, my friend>

What kind of fixture, and are 5500K Hamilton's better than 10000K Ushios? Hi I have a question if I purchase a light fixture that comes ready with 2 MH 175 watt of 5500K Hamilton's  should I upgrade both bulbs to 2 Ushio 10K EACH, plus the 2 actinics, << I think you would like the color better if you did.  So I would go with two 10k Ushios, and two actinics. >> the fixture is ( these are the specs), how should I raise it more from my tank so that its not so close? << Well here is where you get to use your DIY skills.  I like to build wooden frames, but others use PVC.  I guess you should see some local tanks and get ideas about what will work for you. >> And should I take my glass cover from my tank? << I like glass.  I like the idea of having glass because it is much easier to clean than cleaning a bulb.  You may want glass if you have a double ended bulb for UV reasons. >> or should I get a retrofit with the same specs as this one and send to make a canopy for my tank? thank you much. High quality canopy with glossy black exterior and electro-white high reflective corrosion-proof finish for interior of canopy T-1 super quiet ball bearing cooling fan. UV stabilized absorbing lens. Optional 2nd fan for extra heat displacement. This is highly recommended for fixtures with 250W or 400W bulbs and for fixtures with 2 or more MH bulbs. Very useful for reef systems!!! Very versatile. You can upgrade your order to higher wattage and Kelvin MH bulbs. You have the option to chose between: STD (standard output fluorescent bulbs), VHO (very high output fluorescent bulbs), or PC (Power Compact). Remote ventilated, enclosed ballast with 10` power cord Independent on/off controls for Metal Halide and fluorescent lights Amp quick-disconnect plugs to ease connection and disconnection between fixture and ballast 11 1/2" wide and 6 1/4" high. All lamps are included. These are custom-built lighting systems. Please allow a lead time of 3-5 business days for assembly. << System sounds good.  Have to compare convenience to price. >> <<  Blundell  >>

Re: 75 gallon: New Reef Tank Hey Gwen, Alejandro here thank you very much it was very helpful your email, I am really trying to take things slowly. My trigger is going out in a couple days, and I've decided to make a canopy for my tank and buy 1- 175 watt MH and 2actinic 40 watt fluorescents and 2 40 watt full spectrum. My question is what distance should they be from the bulbs parallel to each other? And what kind of reflector should I put on top of my fluorescents?. I know that for the MH I could get somebody to do me a sort of a spider reflector in aluminium will this work? and also I have been testing my water parameters my salinity is 1.024 Ph 8.0 Nitrates are about zero and also ammonium. Water temp varies from 24-27 changes slowly every time I turn on the AC will this be affected a lot with the lights? How do you feed the anemones directly? Thank you very much hope to hear from you... <<Hi Alejandro; Good idea to remove your trigger :) I know you don't want to, but it's for the best. Lighting reflectors...if I were you, I would buy a retro-fit kit for the MH and the fluorescents. There are a number of companies that make these kits, all you have to do is build the canopy and install them. The kits come with reflectors, ballasts, wiring, a fan, and instructions on how to set them up. Very easy to do. I have found Coralife to be the cheapest. You should have the lighting BEFORE you build the canopy though, just to be sure your measurements are correct. I am not sure how you would acquire Coralife products in your country, I assume a web search in your language might find a local supplier, like your LFS. If they do not stock the lighting you want, ask them to order it for you. Coralife is owned by Tetra, and just about every pet store sells Tetra products, so ordering your lighting for you should not be too hard for them. If in doubt, ask them. Good job on testing your water, although the nitrIte level wasn't tested? Your ammonia and nitrites should be ZERO, and nitrAtes should be under 5ppm. Test all three for the first little while, especially after you add your live rock. You should keep track of your levels in a small book, so you can keep track. Water temperature can fluctuate daily, especially with air conditioning and metal halides...all you can do is be sure to install the lights correctly, at the right height from the water, and be sure to use the fan that comes with the kit! It will help reduce heat, as metal halides can shoot your tank temp upwards of 90F if the lights are installed too low, or if there is improper air circulation inside the canopy. Anemones can be fed with a small plastic pipette, which can be found in any Hagen test kit. I like these because you can trim the small tip to make the opening a bit larger, so you can feed chunky foods easily. If you don't feel like buying a Hagen test kit, you should be able to find pipettes at your local drugstore. Ask as the prescription counter. You simply thaw a bit of frozen marine food in a small cup, and suck the food into the pipette, then put your arm into the water a couple of inches from the animal you are feeding, and slowly squeeze the pipette till the food comes out. This way you can control exactly the amount of food you are giving, without risk of overfeeding. Unfortunately, all my shrimp are trained now...as soon as they see my arm and pipette enter the water, they swim up and grab a hold of the end and literally suck the food out before I have a chance to feed anything else with it :P -Gwen>>

Re: 75 gallon: New Reef Tank MHs Hey Gwen, my question was don't Metal halides have to be 12 inches above the water? And if I decide to buy a hood can I lay it on top of my tank without taking the glass cover but this will not be high above the tank as I read in the book that you should place your lights high above. What's best, making a canopy with the backside open but wouldn't this make the light disperse out or making it sealed with some holes in the back and fans? And making the custom canopy? or just buy the hood and place it on top of the tank? I've decided for the 2 MH 175 and 2 actinic 40 watts. Do I have to upgrade the MH bulbs to Ushio or Aqualine or use the ones that come with the hood for some while? What do you think? Thank you very much for all your help. <<Hiya, yes, metal halides should be 12 inches above the water. And MY question was, where did you read that you had to place them lower? I was curious to know if you had read somewhere that a specific company had said you could put their metal halides lower. Didn't make sense to me. Perhaps I misunderstood your last post :) Also, I thought you were planning to make your own hood. With that in mind, I then told you to order your lighting (a retrofit kit) and build the hood AFTER you receive it, in order to properly fit the kit. That way, you could make the hood high enough to house the metal halides with no problem. Many of the stock metal halide hoods have fans included, a good idea for your custom hood. To get an idea of hood height, you can look at pictures of them on the Internet, check out other peoples tank pics and specs, or even visit your LFS and check out some of the metal halide hoods that they have on their display tanks, or in their inventory. This will give you an idea of what measurements to use on your own canopy. Yes, you can leave the back of the canopy open to some extent, many of the canopies/covers sold in retail stores have open backs. It really depends on the lighting. Your reflectors should be doing the job of directing the light downwards, this is why I advised you to buy your reflectors from a good company, they are already engineered to do the job of sending the light downwards. You are supposed to keep the glass cover between the water and your lights, but many of us remove the glass and replace it with acrylic instead. If you choose not to use anything, you will need to wipe the salt deposits off your lights once a week or so. Do this when the bulbs are cold, before they go on in the morning, for example. Wiping off hot bulbs will cause them to shatter. And yes, you can use the bulbs that come with your kit, just be sure that the kit you order does come with the bulbs included, ask if you are not sure. Most metal halide bulbs should be replaced once a year or so. -Gwen>>

Mounting MH pendants in a canopy Dear crew, <Matt> First let me say thanks for all of the valuable information you provide on your site. Now on to the question. I recently purchased a pair of PFO DE HQI, 250 watt mini pendants. I want to mount them into a hood. Can I just mount the metal pendant case to the top of my canopy or do I need to leave some room between the pendant and the top of my canopy for air circulation? <At least you should make sure there is sufficient thermal insulation between the fixture and (especially flammable) canopy structure... this may be just a piece of aluminum... The air circulation question can be addressed later, with measure of your water temperature... some folks get away with simply drilling a hole on either end of their canopy, possibly one or more through the top... others find they have or want to add a fan or two to push air in/out> I have sent the same question to PFO unfortunately they have not responded to my request for information. Any suggestions would be greatly appreciated. Regards, Matt <Be chatting, Bob Fenner>

Lighting upgrade for Reef Aquarium 7/31/04 Dear crew, Anthony answered my original question a couple of months back. First the background. I have a 120 gallon (48x24x24) FOWLR tank. I want to start adding some corals. Based on Anthony's response and some further research I did I was planning on upgrading my lighting to a pair of 150watt DE HQI mini pendants. However now that I am ready to order I have noticed that the price increase to go with the 250s instead of the 150s is not that large. I eventually would like to have a clam or two in my tank and I imagine they would appreciate the extra light. <depends on the clam species... but assuming you like the popular blue crocea or maxima varieties (versus lower light Hippopus, or Tridacna Squamosa or T. derasa types), then yes... a little extra light would be nice> What I wonder about though is how would my starter lower light corals, like mushrooms, do under these lights? <keep them in the bottom third of the tank and perhaps add a few layers of plastic window screen to the top of the tank (removing a sheet every few days until all cloth is removed over a couple weeks for a slow acclimation to new/bright light without having to alter photoperiod> Would it be too bright? <not bad at all... you are still close to the average (5 watts per gallon) for reef tanks> I plan to mount the lights 8" above the water's surface and the low light corals would be at the bottom of my 24" tank. Your thoughts would be greatly appreciated. <if you do 250 watt lights... you may want to go higher off the water... 9-12"> Regards, Matt <kindly, Anthony>

Cover for halides Hello. <Hi Tracy, MacL here with you tonight> Thanks for your support to Aquarium lovers everywhere. <Your comments are very appreciated.>  I have a quick question.  I am setting up a 140 Gallon Reef tank that is a 1/2 circle tank.  I am custom making a metal halide fixture.  What should  the transparent splash cover  be made of?  Glass?  Tempered Glass?   Plexiglas? Acrylic?  ??? <The cover on my pendants is acrylic. Hope that helps. MacL> Thanks Tracy Doherty

GE 10k Metal Halide lamps Hi, I have the chance to buy two 400 watt MH bulbs from a person on RC.com for $25 total.   I asked him who the manufacturer is and all he can tell me is that they are GE bulbs made in Hungary and they are brand new.  They are 10,000k bulbs also.  He won them at a reef club meeting and they have only been fired to see if they work.  Would these be good bulbs to use knowing what little info we have on them at the moment or should I stay with Ushio or Iwasakis?  Thanks, Jeff  <For $25, you have little to lose!  Your corals won't care much what brand they are or where they are made or even what they look like, as long as they produce enough light.  I would give them a shot, and if you don't like the color (use them at least two weeks for them to "burn in" before deciding), re-sell them to someone who doesn't care.  I would guess that they are at least as good as the Chinese made lamps that are becoming very common.  Best Regards.  Adam> Lighting -METAL HALIDE 7/1/04 G'day Boys, <cheers, mate> I am updating my lighting from 2x 4ft fluoros @ 1xactinic blue + 1x 40wtt power Glo........to ..1x 400wtt mental halid+2x40wtt actinic blue fluoros. My tank is 500 liters with soft corals. the tank is near the window so it gets the morning rays as well. <the natural sunlight is excellent, and the total wattage of light (400 on a 500 liter tank) is very fine, but the concentration of it in a single bulb is a bit much. Two 175 watt bulbs would give you a better spread. But if you use the 400... you'll just need to pull it higher off the surface to get the spread you need. I suggest 10-12" minimum (25-30 cm)> how should I set up my timers to achieve the best result. <6-9 hours of MH light will be fine here... start on the low end at first to not shock your corals. You might also use some plastic window screen ("fly screen"/hardware cloth) in sheets on top of the tank (about a dozen sheets) for the first couple of weeks. Pull one sheet off every day or other... this will allow the corals to adapt safely to the new MH lamps> I want to use the actinic fluoros for a night light until I retire for bed. could you provide me with a starting schedule so I don't bagger it up. <yes... very fine. Run the actinics for 10-12 hours so that they come on a couple hours before and stay on a couple hours after the MHs> I've been told that a 400W metal halide is way too much. <around 5 waits per gallon is good for the average reef tank... locked into one lamp over this sized tank is the challenge here> As I'm setting up my lighting this week, can you let me know ASAP, as I've read all the lighting articles on your website and I'm still not sure what to do. TA MATE CHRIS (OZ) <best regards, Anthony>

HOW MUCH HALIDE IS ENOUGH? 6/30/04 Hello,  I am currently setting up a 24"x24"x24" acrylic cube tank to house a 10" anemone, it is one of the carpet anemones, haddoni or gigantea?  Will be basically a specimen tank designed specifically for the anemone and some black percula clowns. (can more than two perculas be kept together). <Kudos for having the discipline to maintain a species tank for your anemone.  Please do be sure to positively ID your anemone as Gigantea and Haddoni have different preferences and Gigantea gets quite a bit larger  Both can grow to sizes that exceed the size of your tank.  "Anemonefishes and Their Host Sea Anemones" by Fautin and Allen is an outstanding resource for this topic.  Keeping more than two Percs in such a small tank is probably risky.  If you do attempt it, let a pair get established and then introduce a much smaller new comer.> Would I be better off with a HQI metal halide 150W pendant or a 250W  HQI pendant? <150w will be fine if you maintain excellent water clarity, but I would probably choose 250w.> Also 10K Aqualine or 20K Aqualine bulb? <Very much an issue of personal preference here.  The 10K will provide much more intensity, but if you prefer a deeper blue appearance, choose the 20K.  If you choose 20K, I would definitely recommend 250w to make up for the lower intensity.> Hang it 9" of the top of the tank? <Should be fine.> Other than the live rock/live sand and percula's, any suggestions as to what else can be kept in this tank , a clam? dwarf angel? etc., or better yet what not to keep in this tank?  Thinking of the long term. <S. Haddoni generally buries it's foot in sediment and Gigantea will occasionally do the same, so I would go with a deep bed of fine sand.  Other sessile inverts are probably OK, but keep that discipline and don't go overboard!  Shrimps, crabs, slow moving fish (mandarins, gobies, etc.) are all definitely out.  You are in a catch 22...  Your tank is too small for free swimming fishes, but the anemone makes it to dangerous for smaller less active swimmers.> Thanks for your time and expertise, Stephen <Glad to help!  Adam C.>

Small metal halides   Hey guys.<Hi, MikeD here> I have a 46 gal. bow front with a 4 39w t-5 lamp. I would like to add some metal halide lighting but I only have about 4 inches of room behind the t-5's to work with (I was out voted 1 to 1 on drilling holes and hanging a pendant) what is the smallest fixture I can buy to fit in this space (4x36). I thought I had good lighting but my green star polyps were green when I bought them and they are more brown now. my colt leather looks great but I figure extra light can't hurt.<My suggestion would be to possibly add another power compact as I'm afraid a MH would overheat a tank that size VERY easily. That's a LOT of heat that you're contemplating in a very small space>

Metal Halide lamps I recently went to a viewing of equipment being auctioned off by a local furniture manufacturing company that is closing their doors. There are a lot of metal halide fixtures, ballasts and lamps being offered. I would like to know if you may have any information on two particular types of lamps that I looked at and would they be suitable for aquarium? << Unfortunately many people have used such fixtures without much luck.  You can find lots of cheap metal halide and mercury vapor lights at home depot and lighting stores.  So far, most of the people who use them, use them on sumps and refugia.  I'm unaware of anyone who ended up being pleased with these fixtures on their main tank.  The real problem was finding ballasts that operated the right bulbs. >> There were approx. 30-35 lamps marked "Optimarc Super Metal Halide Lamp 250watts". The package states that the lamp was manufactured in Germany for the Duro-Test Corp. Fairfield, New jersey 07007. There are no other markings or ratings on package. There were approx. 22 lamps marked the same as above  but were listed on their package as 400 watts. Any idea about how I can find out about these lamps, their Kelvin rating, or if they would be suitable for aquarium use? << Again, it sounds great, but I'd play it safe and buy a light from a local store where you can see how it looks on a tank. >> The Duro-Test website does not even list these bulbs anymore. Can anyone help? The sale is next Wednesday and I understand they want rid of everything!!! Would these be a good item to scarf up or not? Thank you in advance for your help, Malcolm Ayers <<  Adam Blundell  >>

Metal Halide Light Diffusion Hi guys, <Hello, Ryan Bowen with you today> I am building a light canopy for a 125 gallon tank. <Kinda weird- So am I> The canopy is 16 inches tall and will house 2 250 watt HQI fixtures and four 55 watt pc fixtures. I have lined the inside of the canopy with 1/8th inch acrylic mirror. It is light weight and was very cheap. <OK> The only question I have is if the mirror will cause hot spots on the bulbs. <A good reflector will diminish this> I was just wondering as I have read of different reflectors that reduce hot spots. I'm assuming this means hot spots on the bulbs. The mirror looks like a better solution than painting the inside white. <You'd be surprised how well white reflects> It will be very reflective for sure. All the mounted lights are in fixtures with reflectors so I'm assuming that any light hitting the mirror in the canopy will be bounced back from the surface of the water and shouldn't effect the bulbs as much. <It will simply help give the entire tank an illuminated effect, rather than two points of illumination. Sounds great! As with all equipment like these lights, give them a few days to "break in" before you alter your original plans to make adjustments. Ryan> Thanks for any info on this subject. Chris Dial 

Aging MH Ballasts? 5/26/04 Hi WWM gang! Again thanks for everything.... <Always a pleasure!> I've searched the FAQs for relevant articles on MH ballasts/lamps, and couldn't find a discussion on a ballast's lifetime. The questions I have are: How long should a ballast last, do they fail gradually or just "kick the bucket", and if gradually what are the indicators. <Ballasts do fail, but I have never heard of one that does so gradually... They just quit, or in the case of tar ballasts, sometimes burn up.> I purchased a 175W 10,000K Venture from my LFS and replaced one lamp, and the bulb was dead in roughly 3 days. Haven't talked to the LFS about this yet but want to make sure I'm on the right track before I ask for a replacement. I'm hesitant to install another new lamp until I can assure myself the Ballast is not the culprit. TIA, Jeff Hamilton <Hmmm... Could be a couple of things. Bad lamp, bad ballast, or the wrong lamp for the ballast. Try the lamp on a another ballast to be sure that the lamp does not work. Try your old lamp on your ballast to be sure that the ballast works. Every ballast should be marked (could be inside the enclosure) with an ANSII number. The ANSII number of the ballast must match the lamp. For example m57 indicates 175w Metal Halide. Find the number on the ballast and check it against a reference on the internet to be sure you are using the correct lamp. Hope this helps! Adam.> 

PFO 13K 400W Bulb and Hamilton 14k 400 Watt Bulb Considering these bulbs for my SPS/clam tank, have found little on the PFO bulb other than PFO, and of course they recommend it! <PFO has a great reputation for quality lighting systems. I have not heard much feedback on their bulbs, however. I'd go onto one of the hobby forums to get some feedback from your fellow hobbyists who might have used this bulb> On the 14k bulb I've read a couple articles that said they weren't impressed with this bulb. If you have any knowledge or experience with these, could you please share it with me? Thanks Shayn <I have a friend who uses these bulbs in his FOWLR tank, and they are attractive from an aesthetic standpoint. I have not seen impressive coral growth with them, though. I'd choose a 10k or 20k Aqualine for coral growth. This is not to say that they are not good bulbs. Again, I'd defer you to the WWM Chat Forum to see if any hobbyists have experience. Good luck! Regards, Scott F> 

Screening MH Bulbs.. Hi Bob, <Scott F. in today!> I must say, I've have gathered much of the knowledge I need from this place. I appreciate what you guys are doing here. <We're thrilled to be here for you. We have a lot of fun bringing the site to you every day!> I have just bought a Sylvania 150w AquaArc 10k MH for my 4ft tank. It's a Double-Ended type and I understand the glass is not anti-U.V. coated. I have asked a friend of mine to custom made a casing using mirror glasses for the sides and top (for maximum reflection). The bottom surface is a clear glass so that light can pass-through. There is also a small fan to suck out the hot air from the glass casing generated by the MH bulb. <Sounds acceptable for a double-ended bulb. You do want the glass cover beneath the bulb, as these bulbs put out a lot of UV> Anyway, to cut the story short, worrying about the UV effect that it may have on my family, I got myself a 5ft car tint (similar to v-kool, not sure if you have heard of such product) plastic film. Which suppose to cut off the UV and reduces heat transmitted to the car's interior. The film is able to reject 80% of heat rejection, 99% of UV and allows 80% light transmission visibility. I've pasted this film on the clear glass hoping this will reject most of the UV rays. <Should, but it might also cut out some of the useful parts of the spectrum, too.> By cutting off 99% of the UV rays, will this have any long-term ill-effect on my corals? Is there any relation between the UV-rays and PAR? <Good question. PAR may be affected somewhat if the bulb is shielded by the tint, but without a light meter and some other scientific measurements, I'm just speculating here.>  Previously, I was using 4x standard fluorescent lighting and my corals are not that healthy. But a week after I've installed the MH, I can see huge improvements. Corals look "alive". I have intention to fix the 2nd MH on this glass-mirror-casing. But I'm not sure if I'm doing the correct thing by cutting off the UV-rays. <Perhaps you could obtain the type of glass used on commercial D/E fixtures, and you won't have to be concerned about the potential loss of intensity or useful spectrum...or, at least you won't be wondering if the tinting is having an adverse affect!> BTW, does blue tang like eat/nip on corals ? <Blue Tangs may occasionally take a passing nip on a coral, but this is generally incidental to their feeding/grazing activities. These fishes are mainly planktivorous, so they are more-or-less harmless to corals, in my book!> Thank you very much. Regards, Eric <You're quite welcome, Eric! Regards, Scott F> 

MH lifespan 5/7/04 I was given (2) 175 Watt MH German bulbs, which I've used to light a reef tank.  I recently found out that the bulbs were 3000-4000 hours old when I received them.   <no biggie perhaps... I had a Radium last almost 5 years (useful as tested with a light meter). MH lamps generally do not sway much from their original index, and are useful at over 90% of their color for practically the life of the bulb (2-4 years for many)> And I'm fairly certain that this is the cause of the excessive green hair algae in my tank.  :^)    <heehee....ah, no. Not likely at all. Light does not cause algae, light in nutrient rich water causes algae <G>. Seriously, what you have is a nutrient export flaw/problem... and this is categorically very common. Improved protein skimming alone can cure your algae problem in 3 weeks or less> I will be able to afford their (MH bulbs) replacement next month.   <perhaps not needed yet> Until then should I continue to use the old bulbs or should I merely use my other bulbs (two fluorescent bulbs)?   <please do not shock the tanks inhabitants with such drastic and unnecessary changes> I have a little soft and hard coral in the reef tank along with live rock. Sincerely, Josiah <please do take the time to read through our extensive archives at wetwebmedia.com on the articles and FAQs for nuisance algae. Anthony>

Choosing a Metal Halide for a 46 gallon Bow - 5/5/04 First off - FANTASTIC website! <Thanks> I can spend hours on end reading up on things completely losing track of time. <Me too. Now I volunteer here> The team's dedication and willingness to help is nothing short of incredible. <I agree. They have been very supportive of me as well. I continue to learn a lot> I am upgrading lighting on my 46 gallon bowfront tank (36x15x20). I am looking at hanging a 2x175 13000K MH w/ 2x96W 7100 PC about 8" above the tank. <Sounds fine> My hope is to keep a nice mixed reef tank with soft, LPS and SPS corals. Further down on my priority list is maybe putting a clam on the sandbed at the bottom. <OK> Will this light fixture suffice? <I believe so. Just as a side note, I have a 250 over a 20 gallon. It is hot (California) but with a fan blowing over the top of the water as well as blowing over the light, I can keep the tank around 80.8 easily. Gotta top off often though>  Someone said a 2x250 MH would be necessary for clams, <Not for clams. I have seen great clam growth with VHO, T5, PC and of course various other MH. Intensity of the lighting source (PAR output is very important to sustainability of zooxanthellae and photosynthesis. (=survival for corals)> but I'm worried about far too much heat in the summer time (in California). <Could use a fan blowing across the water or lights. Also, look into a chiller. I use an Aqualogic controller to monitor my heating and cooling. A great tool and worth the money if you can afford a fan or the more expensive chiller. I believe your setup will be fine for whatever you choose. I like a mixture of either 6500K bulbs and 10000K bulbs if you have two MH systems. you might like a bluer look and you could put Actinics in the PC system if you want but in my opinion I would go for the MH and forget the PC entirely (unless you already own it)> Thanks! <Thanks for being part of it all! ~Paul> Shaun

PULSE by PLUS Lighting Company Metal Halides...Are they any good? - 4/20/04 Hi, I am looking for information/reviews on a particular brand of Metal halide bulb; 250 W 10k; for a reef aquarium application. <Well, after doing a search on Google ( I assume you probably already did this) I could not find anything on Plus Lighting Company within the first few results pages. Pulse is usually related to a start method for metal halide ballasts. I have not heard of this brand or manufacturer. Anyone out there reading the FAQs please let me know if you have this brand or know of any reviews for their products. Otherwise, I am sorry but I really can't help.> The brand name is Pulse and it is made by Plus Lighting Company. <Never heard of this brand or company> Any information would be greatly appreciated!!!! <Sorry to be of little help. I would try this in the WetWeb forum (other reef forums as well) and try a few other search engines. Good luck ~Paul> Many thanks, Miguel

Adjustable Lighting 4/1/2004 Rich, This message came back to our inbox. I am re-sending to be sure you got Steve's reply.  No need to respond.  Thanks! Adam Raising/Lowering Pendant Lights (4/5/04) Steve (or crewperson for today): <Steve Allen again. Sorry to be slow to reply. I've been having some Internet problems the past few days.>   Thanks for the reply to my email.  To review for others, I asked about adjusting the height of my MH pendants easily like window blinds or pulley-type system (to do maintenance on the tank).  Your reply was: "I hung my pendants with chains from swag hooks in the ceiling. I simply lift up the light and hang links closer to the light over the hooks, thereby raising the fixture anywhere from a few inches to a couple of feet out of the way...".  I have to say that is simple.  However, any ideas for people who don't have the luxury of tallness or a step ladder ;) ?  Rich. <Well Rich, the best I can think of is for your to suspend them by cables from small pulleys secured firmly in the ceiling. You could tie the cables off to cleats in the wall. Then untie them, raise and tie off again when doing maintenance. I will also send this to other crew to see if they have any ideas.> MH lamps, ballasts reference Hello all, <Jason> I see where a lot of people have questions about lighting. Seems most are concerned about which ballast to use or which bulb.  I just finished reading this post on reefcentral. http://www.reefcentral.com/forums/showthread.php?s=5fcaa84c7cbae077c75968cec8969714&threadid=254667&perpage=25&pagenumber=1 It is about par reading on different MH bulbs with different MH ballasts. Be prepared, its about 40 pages but full of information. Just thought I'd pass it along. Jason <Thank you for sending this along. Will post. Bob Fenner> The Bulbs Are From Mars, The Ballasts Are From Venus (Bulb/Ballast Compatibility...)  I just set up a 112 gal tank I haven't run for years. It has two 175 watt MH lights running off two separate ballasts. I think they were originally from Coralife some 10 years ago. One of the ballasts went bad, and I replaced it. I checked the specs, its the same as the old one, and I know I hooked it up right. I put two new Ushio 175w 10,000k bulbs in. The new ballast will start to run the light but after about 20 seconds it goes out. The other ballast is running the new Ushio just fine. Any ideas what is going on? The lighting dealer where I got the ballast doesn't have a clue. Are there compatibility issues with certain  ballasts/lights?  <There most definitely are. I'm not an electronic engineer, but as a hobbyist who has messed with his fair share of metal halide bulbs and ballasts, I can assure you that there are many different possible ballast/bulb combinations that won't work.>  Is it worth spending the bucks on an electronic ballast that claims it will run any light?  <Well, I am admittedly biased towards electronic ballasts. They are very energy efficient, and many brands will run all sorts of bulbs. They are generally a bit more expensive, but they tend to be less expensive to operate in the long run. I'd check compatibility issues with Coralife on your specific ballast/bulb combo, but I would also look into the electronic ballasts as a possible future option. Regards, Scott F.>  Thanks for your thoughts. BTW, your site is wonderful. Thanks.

Ballast Question 4/1/04 Hello  Hope all is well. I am getting 2 250 watt ballasts for my tank(125gal). I am trying to decide which way to go as far as ballasts. I was searching online and read some pretty good things about PFO. Others are Blueline, Icecap, and the one that hellolights.com sells the name escapes my mind). PFO makes a "dual ballast". 1st question. Is it better to go with a dual ballast? <Probably more cost effective up front.> 2nd question(s). What are your opinions on electronic ballasts? Have you ever tried one? Were you satisfied with it? Or any warnings about them? <I have not used them, but I heard nothing but good about them.  My next MH ballast purchase will definitely be electronic.> 3rd question. Could I go wrong by using PFO? Do you recommend any other? Thank you for your answers or opinions. Jason <PFO products have a great reputation, and are highly recommended for conventional ballast choices.  My understanding is that PFO does not actually make ballasts, they just build enclosures and install widely available ballasts in them.  There is nothing wrong with that, you just pay a premium for a nice pre wired heat sink enclosure.  PFO sells different ballasts for different lamps. The ballast you choose will limit which lamps you can run, and this is more true of conventional ballasts than of electronic.  Sunlight Supply and others sell products like PFO's, and likely use the same components.  Some incorporate built in timers and auxiliary outlets.  I would suggest choosing electronic vs. conventional and then shop price and features.  If you go conventional, you will have to decide on the type of lamps (Mercury/Iwasaki, pulse start MH, normal MH) you wish to run and get the appropriate ballast for it.  Best Regards.  Adam>

Raising & Lowering Pendant Lights (3/31/04) To My Favorite Crew: Do you guys know of any existing way to adjust the height of my MH Pendants, say for cleaning the tank, water changes, etc.?  Something that can be done easily and often, kind of like window blinds or some kind of pulley system.  I have looked to no avail as of yet.  Thanks, Rich. <I hung my pendants with chains from swag hooks in the ceiling. I simply lift up the light and hang links closer to the light over the hooks, thereby raising the fixture anywhere from a few inches to a couple of feet out of the way. If yours are suspended by the power cord like some lamps, you ought to be able to find a clip that attaches lower and can be hung on the hook. Steve Allen.>

Lighting and supplementary equipment questions 2/26/04 Dear Mr. Fenner,  I am 11 years old and have a 60 gallon reef tank. <Hi Evan.  Adam here today.  Congratulations on such an early start to the hobby!  So many years you have to enjoy it!> I check my water parameters each day and perform water changes 10% every month. I was thinking about adding to my lighting system of two 96 watt power compact bulbs. I was thinking of adding two 150 watt 20,000k metal halides. If I did this would I need  a chiller or could I use three of four cooling fans? <If your house is air conditioned in the summer, you may not need a chiller.  A couple of fans will often work fine.  You will need to consider the noise, appearance and added evaporation in your decision.  If you want to keep animals that you really think need halides, you may want to consider the compromise of a single MH over the center.  That way you will have areas on the sides for lower light animals.> I was also thinking about adding a calcium reactor and a nitrate reductor to my tank. Would these be necessary? Would i need a sump for these? Could they sit under my tank using plastic tubing to get and return the water to my tank? Could you please e-mail me back. Thank you in advance.  Evan Morris Santa Monica, CA <You can run these devices without a sump, but you might need pumps to move the water through them.  A calcium reactor is nice for the convenience of not having to make daily Ca and Alkalinity additions, but is not necessary.  A nitrate reducer should be totally unnecessary for a properly set up and maintained reef tank.  If your nitrates are over 10 or so, you should correct the source, not just try and eliminate the nitrate.> P.S.  I loved the Conscientious Marine Aquarist. It was a huge help for me when I started reef keeping. I have read every page at least 3 times each. <Bob sees all of these messages, even when he doesn't reply personally, and they are all very much appreciated.  Best Regards, Adam><<Ah, yes. RMF>>

A VERY Bright Idea! (Lighting Upgrade) Hi all...... <Hey there! Scott F. at the keyboard tonight> Quick Q. I have access for free to a 400W Metal Halide upgrade kit (the whole thing including bulb). The bulb is a 4100K bulb. If I use this along with a "true" actinic HO Fluorescent bulb, will I be ok to keep my current soft corals, zoo's and anemones happy...? Jess Bansal <Well, Jess, to be quite honest, I wouldn't use any bulb less than 6,500k. 4100k seems like it would be REALLY yellow! I wonder if it was not originally intended for aquarium use. However, it was not that long ago (well, maybe about 10 yrs or so) that 5,000k bulbs were considered state-of-the-art in halides! Personally, I'd opt for a 10,000k or 20,000k bulb, myself, as these bulbs provide more "useable" spectra, and just plain look better! And, if you are upgrading from either another light source (i.e.; VHO. PC, etc.) or lower wattage halides, be sure to carefully acclimate your corals to this higher wattage, so you don't fry 'em! Hope that your "bargain" works out! Regards, Scott F.>   

The Right Light? Dear Crew: <Scott F. your Crew member today!> Thanks again for the great website.  I have read your FAQ's and articles about MH lighting with great interest.  Here is my situation:  I currently have a 55gal (48x13x20) tank w/130W PC's.  I am going to get a bigger tank this year, probably a 125 (72x18x22).  I would like to keep some clams & SPS, so I am looking at MH.  Also, I believe HQI DE bulbs and fixtures will give me the best for my money. <I agree!> Now, according to Bob's response in one case, with "some" clams and SPS, I should be able to go with 175W lamps. However, I have only seen HQI in 150W and 250W flavors.  The difference in price is about $20, so it would seem wise to get the 250W.  However, I do not wish to have the extra light if I do not need it.  I could probably go with 2-150W lamps for the 55 now, and get an extra one when I get the 150gal.  I thought about 2-150's and then the one 250 later, but I am not sure how I would feel about the spotlight effect (I assume there will be one). <With well-designed pendants, such as Sunlight Supply's Reef Optix III's, or the new PFO mini pendants, the "spotlight effect" that you refer to is usually not noticeable. I use a mix of 150watt and 250 watt HQI pendants over a 20" high tank, and have been quite pleased with the results. It's never a bad idea to look into the 250 here. Clams do require intense light, so at least one 250 would be nice to experiment with!> Before I forget; I know some of you don't like to say, but which would you pick of the 2 choices I have for either 150W or 250W: 1) PFO HQI ballast, Aqualine10K DE HQI Bulb and PFO HQI Mini Pendant *OR* 2) IceCap Electronic HQI Ballast, Ushio or Aqualine (AB) 10K DE HQI Bulb and Sunlight Supply Reef Optix III Plus Horizontal Reflector. <I like #2, and use this combo myself> About choice #2, I have seen some vendors insist that the Sunlight Supply Reflector must run with Blue Wave Ballast.  If this is true, what makes the IceCap okay in this case?  Is there some sort of overdriving or trickery going on here? <Not true at all. Myself and many of my reef nerd friends use the RO III/Ice Cap combo with great results! I'm not sure if this is true or not, but somebody "in the know" within the aquarium halide lighting market told me that the Blue Wave ballast is essentially the Ice Cap in a different housing...Again, I don't have any verification of this, but it may be worth checking out> Hey, thanks a million, Rich. <My pleasure! Regards, Scott F>

Lighting Design Dilemma! Hey guys, I asked this question earlier this week but never got a response. I thought I should resend it incase it got lost in neverland. If you have it and are just busy or decided not to answer because of more important questions out there, I understand. Regards, Jason PS. I forgot to mention in the message that I was planning on using a DSB so the actual amount in the water column would be about 16 inches. Maybe 175's would be enough? <Hmm.. Don't know where it went- but I've got ya' now! Scott F. with you today!> My People, I have ordered a custom tank and waiting on its arrival to the LFS. It is 60 long, 24 front to back and 20 high (drilled of course). To me, the front to back space is important. I feel you can make some really nice aquascape with more surface area on the bottom. <I agree! Tanks with wide front-to-back footprints are great to aquascape> Now, as soon as I receive my tank, I am going to start building my stand. I have had this tank in the plans for about a year, and still some time before its up and running but I'm not rushing anything. For once, I want to do it right the 1st time. <Excellent!> I am planning on a enclosed canopy. I was sold on VHO but I think I can swing MH lighting. I need to have my mind made up by the time I'm ready to build the canopy because from what I have read is MH need to be 10-12 inches above water surface, whereas if I went with VHO, the canopy would need to be shorter. I'm 80-20 sold on MH now though. I'm thinking about 2 250w MH with 3 actinic and 1 10k VHO to come on 2 hours before and 2 hours after MH's. Is this a bad idea? <No- I think it's a great idea. HQI halide pendants can give you great flexibility and efficiency, and will work well in a canopy like this!> In this configuration, what K should the MH's be? <Really depends on the needs of the animals that you intend to keep, and your sense of aesthetics! I am partial to a more "blue" look, so I use mainly 20,000k bulbs, but I have planned my animal population around my preference. Most hobbyists seem to like a mix of 10000ks and actinic supplementing for more blue.> Should I go with 175's? I have always wanted a Crocea Clam (and some SPS's) is why I am doing this, if you were wondering....I will install fans or chiller if needed. <I'd go with 150watt HQI pendants. You will definitely need fans in the canopy to provide cooling, and a chiller may not be a bad idea> Again, I want to do it right the 1st time. Any advice you can provide will be most helpful. Seems the closer it gets to "go" time, the more I think and plan and ultimately, get confused and undecided. ha-ha. < Not an unusual occurrence, especially with lighting! I really feel that, if you plan your lighting package around the needs of the animals you intend to keep, you can't really go wrong> On a totally side note. I use formula one, Mysis, and Prime Reef foods. <All excellent foods> I supplement with VitaChem, Selcon, and Garlic Extreme. I squeeze the juice out of the food when it thaws then dose it with one of the 3 supplements. Is this wrong? Am I squeezing out the "good stuff" or just pollutants? <If you give the food enough time for it to absorb the supplements, you should be fine. Better yet, thaw and rinse the food first, give it a little squeeze, and then soak with your supplement.> Best Regards, Jason <Glad to be of assistance! Scott F>

Lighting 3/20/04 Hello,  I am going to purchase some new metal halide bulbs for my 120 gal tank  18" deep. I have 2 actinics 03.   My question is what temperature bulbs should I get 6,500K 10,000K or 20,000K or something I have not mentioned ?  I have 2 175w sockets. <There are a couple of factors to consider.  "Warmer" lamps (lower color temps) produce more intensity and therefore better coral growth.  Some folks claim that higher color temperature lamps produce better coral coloration.   Mid range lamps like 10,000K fall in the middle and strike a compromise between the two.  There is also a major component of personal preference of the lamp color.  Some folks like the "natural" look of lower color temps and some folks like the bluish look of higher color temps.> Should I buy both the same or two different temps.? <Again, this is largely personal preference, but often looks weird when the ends of the tank are different colors.> Current residents 2 torch corals, 1 Caulastrea, 1 Euphyllia divisa, 1 Wellsophyllia, 1 Bubble coral, 2 Percula clowns, 1 Pterosynchiropus splendidus, a couple mushroom colonies and all kinds of good stuff that's been growing on my rock for the last year and a half. <Most of the corals you listed should be acclimated carefully to large increases in lighting.  Consider raising the lights up high and lowering them a few inches a week to their final location.> Thanks again for your help!!!  Rob<Glad to!  Adam>

Metal Halides Greetings Anthony, Bob and the rest of the crew. <Cody here today.>Today's question is in regard to MH lighting. I've perused the various boards on WWM regarding MH lighting, but sadly, the more I read the more confused I get. My 75G reef has been up for one year as of this week. All is well thus far. I have been going with softies (xenia, polyps, leathers, etc) with the exception of a couple of open brains (trachys). My wife has been insisting on a clam from the time I set up and cycled the tank. I explained to her the need for more intense lighting and she has finally broken down and given the okay for me to procure the halides. Through the drygoods forum at RC (can I say that?) <Of course, I spend tons of time there myself!  They are a great place for info with many different opinions.>I found someone who was upgrading his system and letting go of a pair of 250W moguls w/spider reflectors, ballasts, etc. He is including 3 mo. old (so he says) bulbs but isn't sure what brand they are. He says the lighting is a bit on the yellow side. First question is, what brand and/or type of bulbs would you recommend. <This all depends on personal preference.  Every one has different opinion and you sill have to go check out some tanks with different bulbs.>If I use bulbs with a bluer hue, should I still run actinics or will the MH bulbs over-ride them? <If you use a very blue bulb like XM's you shouldn't need any supplements but again it all depends on personal preference and is a trial and error kinda deal.>Currently, I have a Coralife 48" fixture with 2 65W 10000K and 2 65W Actinics plus 3 additional 65W 10000K in a home-made set-up. If Actinics should be used with the halides, I figured I could use the home-made set-up to house them. Next, in going with the spiders, what about the lack of any type of UV filter on the fixture? Is this something that needs to be addressed? <I would definitely put some type of UV filter over these.>Finally, how close (or far) should the MH's be mounted from the top of the tank, and if I do use the PC Actinics, should they be mounted lower or at the same height as the MH's? <MHs should be about 8-10 inches away and the actinics can be mounted closer.>Oh yeah. One more thing. Should I move the corals to a lower level in the tank and gradually move them up or just begin using the Halides on a shorter cycle and gradually increase the time they are on? <Definately, I would move them to the bottom (the brains should already be there) and gradually move them up so they can adjust to the new lighting.>Thanks once again for all of your help. I look forward to hopefully meeting some of you guys this June in Chicago.<Thank you for writing!  Don't know if I'll make it but there will be quite a few of us there!  Cody> Greg Berkeley, IL

Metal Halide Bulbs 2/9/04 This email is for Anthony if possible.  Anthony, I am a big fan.  I really enjoyed your book of coral propagation.   <aw, thanks kindly. Its redeeming and inspiring to hear my friend> Are you going to do a continuation? <yes... its my priority right after I finish the NMA volume 2 "Reef Fishes" this year with our friend Bob> My question is concerning bulb choices for my 75Reef.  I have mostly SPS, but a few zoos and LPS.  I have 2X175W Ushio 10ks <one of the best bulbs overall... perfect for this sized tank... and would have been my choice too> and 2 URI VHO actinics.   <good for aesthetics, but not needed for coral health (enough blue in MH lamps) and they are nearly ineffective if more than 3" off the water surface (check with a Lux/PAR meter to confirm)> My bulbs are about 5 months old.  I plan on replacing my bulbs every 6 months or so to avoid a big shock to my corals.    <needed for fluorescents... but not the halides. They go 18 months easily... perhaps over 3 yrs for some> I am considering replacing my Ushios for the new XM 20ks.  I have seen these bulbs on an aquarium in Gainesville and they look great.   <aesthetics yes... coral growth, no. Stick with the Ushios for best overall> They appear very white/blue and really make the corals glow.  I would like just a little more "blue" than what I get with my current bulb configuration.    My concern is it will not be enough light compared to the Ushio 10Ks.   <correct> What do you think about the change? <not recommended. Just get your VHO blues closer to the water or add an extra pair if you like for color> Thanks as always for all your help. Andrew <best of luck! Anthony>

HQI For The Mogul Guy (Replacing Mogul Halides with HQI) Hi all, got a few questions and I know you guys are pros, so let the questions begin. <Scott F. at the ready today> I recently upgraded my lighting on my reef aquarium from 2 175 mogul base MH to 2 250 watt HQI bulbs, I plan on venturing in to the world of stonies and clams pretty soon even thought about an anemone to host my maroon clown... just needed assurance if that set up would be considered bright lighting for a 75 gallon aquarium... <For most SPS corals and/or clams, that would be a pretty bright lighting setup. For softies and some LPS corals, this could be way too much!> I was also reading and article, it stated that HQI lighting is significantly brighter that the standard mogul base MH lighting. <Not so much "brighter". It's also a function of efficiency...> The reading indicated that a 250 watt HQI is close or equal to a 400watt mogul base metal halide...is that true. <In some instances, yes- the PAR value of some 250 watt HQI bulbs in an efficient reflector is equal to or greater than some 400 watt mogul bulbs> Also, I just acquired a Condylactis anemone. He seems to be doing a lot better, purchased from a LFS that had a tank full of them under 1 NO light which I know is not enough light. <It isn't!> I was wondering, if I decided to add a BTA, or even a nice Green Carpet would chemical warfare be a problem. <It very well could be. I highly advise against mixing anemones in anything but the largest of systems. The potential for problems is just too great, IMO> From ya' boy ***Chris*** <Well, Cris- sounds like you're on the light track with the lighting...Good luck with your animals! Regards, Scott F>

- The Holy Grail? 175 Watt, Double-ended Metal Halide - Greetings!, having read and read, I am amazed at the amount of information you dose out on a daily basis. Having been on the reading end for so long,  I figured its time for me to ask a question since I can't find anything on this: Are there currently, or future plans for a 175 DE bulb that you know of that will run on today's electronic ballast? <Well, I'll be honest - no one tells me anything. I see new products about the same time you do, sometimes a little earlier if I go to The Big Trade Show but also sometimes later when folks write in and ask about it. I've certainly not seen anything lately. Might have to wait for the big report back from Interzoo in May.> Thanks Chad <Cheers, J -- >

Metal Halide lighting Hi Bob,   <Hi Larry.> I'm up grading my 30 gal reef tank to a 55 gallon.  I currently have hard and soft corals with a maxima clam.  I am trying to decide on whether to use a 260 watt power compact light fixture or a hood with 2 -175 watt 6500K metal halides and 2 actinic 20 watt fluorescent bulbs. My question is how often do the MH's have to be replaced and are they more cost effective in the long run. <Halides, (with the exception of 20,000k bulbs which are overdriven) on average, need to be replaced every 11-12 months. In the long run, halides are cheaper than fluorescent lighting. Watt for watt, they cost the same to run than fluorescent lighting. Watt for watt, halides emit the same amount of heat as fluorescent lighting does. As an example, 400wts of halides would have the same heat as 400wts of powercompacts would. <<Graham... not correct. The measure of wattage is consumption of electricity... the heat generated is far different. RMF>>   If you didn't already know, Metal halides release all of their energy in one small area which is why halides often seem hotter than fluorescent lighting. In the long run, halides can often save you money.> I like the shimmering effect of the MH's but the initial cost is twice of the power compacts which will have 4- 65 watt bulbs, 2 -10,000k and 2 actinic.  Also, if I go with the MH is there any benefit with going with the 10,000K bulbs vs. the 6500K  aside from the whiter appearance.   <The 6,500k bulb will have slightly more intensity, although overall, it won't make an extreme difference.> I feel the mixture of the 6500K bulbs with the actinic blue would give a nice appearance to the tank.  I appreciate your input and your web site which has been very helpful in the past.  Thanks, Larry. <I would actually recommend you buy 2x 250wt halides than 2x 175wt halides. The 250wt bulbs will give you much more intensity and will allow you to keep many more inhabitants, especially if they're going to be placed at the bottom of the aquarium. The cost should be about the same as the 175wt halides (of course, depending where you looked). However, Either choice would be good. Take Care, Graham.>

Lighting 2/9/04 Thanks for your quick response.  Just one more question before I spend more money on this tank!  I asked the guy I trust the most at the LFS why he recommended 400w.  I told him what you had said about the tank needing to be more then 30" deep to even consider them.  He told me that he recommended them because my tank is 27" deep plus the canopy being 10 1/2" deep = about 37" deep.  I do not plan on buying another canopy... so with that being stated would you still recommend I reduce my W's?   <its tough to say... the corals you are keeping have no need for such bright light and you do not need to pay the extra electricity for a flawed canopy/installation. But then again, the cost of correcting it will be a short term expense that you may not wish to suffer. If you think you may get a bigger tank in the next few years, then do keep the 400 watt lights (begrudgingly <G>)> Again last time I will ask, and from all the reading on the WetWebMedia site, I really do love your sense of humor...keeps the reading entertaining... thanks again, Phil <no worries my friend. The corals will adapt likely so. And if you can endure the heat (more fans to exhaust perhaps) and expense, no change is needed. Anthony>

Adding MH Lighting 2/5/04  Hello again! You guts are great. Thanks for the help in the past.  <Hi Jim. Glad you have benefited.>  I have a 120 gallon tank that is 4'x2'x2'. I currently have 700Watts between PC and VHO. I want to get rid of the PC and change to a 250Watt 10K MH (I already have the MH). The problem/concern that I have is that I currently have my lighting under a hood. If the MH fixture can fit under the hood, will it be okay to run with two 4'' fans for cooling?  <It should be, but it is hard to guess. Depending on where you live, whether you run A/C in the summer, use a chiller, photoperiod, etc., the fans may or may not be enough to control heat.>  Will there be an issue with placing the fixture on top of the glass cover?  <If you meant the glass aquarium cover, yes. The heat from the lamp may dangerously overheat the glass cover if it is too close. Also, most reef keepers don't run glass tank covers because of the amount of light the block, even when clean.>  Another idea that I had was to remove the bulb from the fixture and mount it to the top of the hood with a piece of sheet metal to deflect the heat from the hood and still using the reflector. I would still use the fans to cool the light, but I am not sure if this is a good idea. Any other suggestions to improve lighting and still keep everything under the hood?  <If your MH is contained in a pre-made fixture, I would try to use the fixture as is. It should be at least a few inches from the water surface to protect it from serious splashing. I would consider cutting a hole (or other wise re-engineering the hood) and recessing the fixture in the top of the hood before I would dismantle the pre-made fixtures. Best Regards. Adam> Jim Martz Sr. 

Sunburst Metal Halides 2/2/04  I recently saw halide bulbs called Sunburst made by Aquatic Lighting Systems that are 12000K. Do you folks have any experiences with these 175 Watt bulbs? Being 12K I'm sure they would have a fair amount of blue in their spectrum and could probably be used without supplemental actinics, would this be correct? Thank you for the advice and for the help you folks give so freely. Matt  <Hi Matt. I have seen these lamps, and would consider them to be similar to Radium 20,000K in appearance and intensity. IMO, they are quite blue (too blue for my taste, even without actinics, but this is very subjective), and for this you sacrifice some intensity. Kelvin rating is based on a complex calculation derived from the spectrum of the lamp and is often simply made up by the manufacturer, so it is not a reliable indicator of what the appearance will be. Best Regards. Adam>

Metal Halides for now and in the future - 1/28/04 Hi, I currently have a 55 (48x12x20) gallon tank with 440watts of VHO lighting, but I am considering an upgrade to MH lighting. <Very good. Any reason why?> Here is my dilemma.  In a year or two, I would like to upgrade to a larger tank with dimensions 60x24x36, <By my calculations (if this is the inner dimension, would be about 225 gallons approximate) so I would like to buy lighting that can be used in both tanks.  My plan would be to buy one 250W MH light now, and add a second with the new tank. <Well, if my calculations are correct you will probably want more light than that for the future tank. I am thinking of maybe one 400W now and add or another or maybe even 2 more later.>   But I am wondering if 1 bulb is enough in the 55 G tank, and if 250W bulbs are sufficient for the depth of larger tank. <one 400w would be ideal for the 55 gallon with no need for actinic supplementation (unless you want more visual aesthetic balance, which I don't really like myself) but once you move to a bigger tank you will want to add a few more metal halides to maintain intensity and PAR levels> Would 400W bulbs be better in the large tank? <Yes>  What configuration(s) would you recommend? <one 10K metal halide for the 55 gallon and three for the 225 in the two 10K, and one 6500. Of course, this all depends on being able to mitigate the heat issue and what type of animals you intend to keep> Thanks, <Sounds good. ~Paul> Dave

MH Question! <Ryan Bowen with you this morning> I am setting up a 68 gallon reef ( 48x18x18). I am wondering what MH lighting to use. <Lots of choices, eh?> By the Book of Coral Propagation, <One of my Aqua-Bibles as well> I should be able to use 175 watt MH as the tank is only 18 inches deep. <OK> I plan on having brightly colored SPS and clams only. Will 175x2 work with 2 VHO's or would you go to 250x2 with VHO's? <Two 175's are perfect, as long as you are: A. Buying a quality electronic ballast, and B. Marking your bulbs on the calendar, don't miss a replacement.> Are the electronic ballast worth the extra price and do you think double ended bulbs are the way to go? <Haven't used double ended bulbs myself, but I have heard good things.  Try the forums over at http://www.wetwebfotos.com for some feedback.  As for the electronic ballast, it's a must.  It will save you money in the long run!>  To complicate the matter, I have a 400 watt MH retro from my previous tank. Would dual 400 watt MH be overkill? <Likely> I want to purchase the right thing the first time and not have to keep upgrading as it cost too much money in the long run. <I know it!  I think you're on the right track.  Lighting is certainly important when you're raising photosynthetic animals, but don't forget about current!  It's nearly as important.  Good day, Ryan> Thanks Wellington

New Metal Halide Lighting design?? - 1/25/04 Hello Crew! Unbelievable site! <Yes indeed!> I've just devoured Mr. Fenner's book and I use this site daily. <Great to hear> I am a fairly new aquarist and have some questions regarding MH lighting. I specifically interested in understanding the reasons for the height recommendations regarding MH lighting. <Well, heat for one, moisture, and intensity.> I've seen the recommendations for 6-10 inches off the water for 175 Watt and 12 inches for 250 Watt lamps. Are these heights designed for safety, light levels, or heat dissipation? <All the above, mate> I realize that the short answer is probably "yes". Why would you get a larger wattage lamp and then raise the height over the tank? <I think you can "guess" the answer here as well. The greater intensity does little in dissipating the heat but the output even at a few inches is still great enough to promote growth in the coral thus the elevation in the higher lighting fixture> I am in the midst of designing a 125 gallon reef tank. I'm also designing my own MH light fixtures. <Ahhhhhh> The fixture utilizes a "cold light" reflector that reflects 95% of visible light but transmits 75% of Infra Red light (heat). The fixture also utilizes a "hot mirror" as a lens that the lamp shines through. This "mirror" transmits 95% of visible light but reflects 75% of IR (heat). <OK> The result is a lamp that produces only about 15% of heat at the lens of a "normal light". The balance of the heat ends up behind the reflector where it's easily dissipated into the air via a chimney type heat sink. <Sounds interesting.> I've designed the light much like a fat, squat version of  a "Mag Light". The entire fixture is watertight (indeed submersible). <Hmmmmmm> Given the fact that this light adds very little heat to the aquarium and the fact this it is watertight, could I place this light very close to the water (I'm thinking 3 inches) and use a lower wattage bulb than I normally would? <Well, when designing a "new" type of light I suggest you experiment as much as possible> I realize that there are many factors that affect the light decisions. <You said a mouthful> I'm interested in a apples and apples comparison. <Well, not being a light guru or designer for that matter I only have the basics of lighting under my belt. Why don't you produce such a comparison? Read some of the articles by Sanjay Joshi around the net and in some of the old salt aquarium review periodicals.> In other words, given an aquarium with a perfectly matched "normal" 250 Watt lighting system, could I use a lower wattage bulb, hung closer to the tank, using my design, assuming all lighting characteristic were identical? <Is possible. In fact I have seen some pretty amazing coral tanks without the use of Metal Halide or even Power Compacts for that matter. I suggest you create a hypothesis, and set up the experiment yourself and publish your studies. Your basic theory seems plausible given light output but remains to be seen until your "test" device is ready for trial. Give 'er a go! ~Paul> Thanks so much for your insight and fabulous site!