Substrate and Bioballs 8/19/05 Hi, I have a few questions. First, I've read on your site that crushed marble is not a good choice as a substrate, what is the actual difference between marble and crushed coral that makes marble a bad choice? <Well, to be very general, crushed coral tends to dissolve easier in the higher ph of a marine tank, and provides some buffering and dissolved mineral content. Marble tends to dissolve much slower.> And does that matter if I'm only using the marble as a one inch substrate for looks only? <You could, but both of these materials are generally found in very coarse grades, and coarse substrates require a great deal of attention, even at shallow depths, as they will tend to trap detritus. Accumulated detritus can lower water quality and lead to outbreaks of nuisance algae. If you are intending to maintain a sandbed of any depth, I'd tend to prefer a very fine substrate, like the oolithic aragonite materials in the "sugar fine" grades.> Also, I'm changing the main filtration on my tank from a penguin BioWheel with ceramic noodles to a sump with bioballs. Most of the advice on your site says to use live rock and a deep sand bed instead of bioballs because of the nitrate factor. But I don't have room for a deep sand bed, and as far as I know the penguin/noodle combo produces lots of nitrates too but I was able to keep my nitrates at zero by using a Zeolite (I think) type medium that has the right size pores for anaerobic bacteria to live in. By my thinking, if I was controlling the nitrates before then switching to bioballs shouldn't make a big difference - is that right? <Well, bioballs offer a huge surface area for bacteria to colonize on. Possibly even more surface area than the ceramic noodles. Either material is excellent at reducing ammonia and nitrite, but both become "victims of their own success", removing ammonia and nitrite, while accumulating nitrate. Perhaps you could utilize a deep sand bed in your sump. Or, you may want to experiment with a very good protein skimmer and your aforementioned shallow sand bed in the display. Many aquarists are successfully forgoing sand beds altogether. More than one way to run a system out there...> Finally, as I said I'm going to take out the BioWheel so I was planning on running the BioWheel and bioballs together for a few months before taking out the wheel. Given that the it has been the main filtration for two years or so, do you think taking out the BioWheel suddenly will cause a problem? <May not cause a problem, but the phasing out of a very efficient biofilter for a new one is always potentially tricky. Be sure to phase out the old system slowly, and monitor water quality along the way.> Thanks for your help. <My pleasure. Regards, Scott F.>

Substrate for pearly Jawfish How are you guys today? Can you tell me what type of substrate is good for a pearly Jawfish and blennies? Fine sand or something more coarse? For Jawfishes,  a mix of some fine (a few millimeters) and larger (several millimeters) and some rubble (shells, coral bits) is best... to allow for digging, tunneling. There are too many types of blennies of too many different modes of life to be overall general re their needs... sifting types are best with fine (1,2 mm.) sand. Bob Fenner>

Rockin' In The Rubble! (Creating a Rubble Zone For Centropyge) Crew: Current setup: 55gal FOWLR w/inverts (snails and hermits), 39lbs. LR, 4-6" DSB, 800gph flow, 10gal QT. I am interested in two Centropyge Angels: loricula and flavissima.  I have formed the opinion that they could both work in my aquarium (feel free to insert rebuttal here). <Rebuttal: It can work in a large tank, but in a tank less than 5-6 feet in length, it could be a constant battle between the two fishes...I'd be hesitant to try this in a 55> On your Centropyge pages it is written: "Habitat: Consists of coral and rock rubble, with lots of caves and crannies."  I would like to add some rubble to benefit these fish (if not for the sheer joy of saying "rubble" every time I show someone my tank ;D). <Dude- you're speaking my language! I always refer to one of my tanks as a "simulated rubble zone" (yep- I'm a fish geek...)> Should I: a) buy it packaged? <Nah!> b) "hammer" out my own from live or base rock? <That's what I'd do, or get smaller pieces of LR from your LFS- they'll love you for it when you buy 10lbs of 2-3 inch pieces of rubble...you'd be surprised at how much rubble it takes to get a pound of live rock rubble) c) use crushed coral that I already have? d) don't bother, it's a waste of time/nothing but trouble? e) none of the above? <Again, I'd either buy some smaller rubble-sized pieces, or take out a hammer and smash out some on your own> Also, what is a good "rule of thumb" (not that again!) for number of "caves and crannies" for my aquatic animals?  Is 1 or 2 hiding places per fish good enough?  Thanks a million, Rich. <I'd create as many nooks and crannies as you can to offer numerous territories and hiding places for your fishes, even if you're just going to keep one Centropyge (I'd go for the Flame Angel myself..). And I DO encourage you to keep just one in this tank...but you could add some cool blennies and other small fishes for an interesting rubble setup. Rock on (I couldn't resist that one)! Regards, Scott F>

IT'S ONLY BLACK IN THE BAG. . . Hi Gang: <Chuck> Not a question, just a comment that may save someone a lot of grief. A fellow reefer told me about the CaribSea Tahitian Moon jet black sand. He wanted to redo his 150 gal tank substrate with it. . . I did some inquiry, and found out it's aragonite (I was even more excited at this point; thinking how cool a reef would look and how well the colors would 'pop' with a black DSB). . . then experimented by using some in a 12 gal nanoreef cube. Bottom line? The slightest bit of detritus (the kind you get in any well-maintained tank) makes the substrate look awful. [Sort of reminds me why I didn't order a black car. . . once I realized I could see fingerprints on the door at the dealership showroom.] Bottom line, this stuff is absolutely beautiful. . . inside the bag at the LFS. Which, IMO, is where it should stay. Chuck <Thank you for sending this along. Bob Fenner, who's cars are white>

Two More Questions (marine substrates) Bob, I have a few questions I left out of my last email. First has to deal with substrate. I have a pistol shrimp and two watchman gobies; right now they are burrowing all throughout the live rock structure and having quite a happy time of it. Would it make any sense for me to add some larger size live sand to my bed of 100% Fiji Pink live sand? <Yes... easier to have the burrows hold their shape> If you are familiar with the names, I was thinking of "Bermuda Pink" or "Super Reef" size sand, and just a little to let them play with the variation in their burrow a bit. I have had someone else say not to; what's your take? <Really like the Bermuda Pink> Second, are you familiar with compact fluorescent lighting? If so, how does it compare to normal fluorescent, in terms of brightness and bulb life. My info says that they are 3 times as bright and last 12-18 months. However, someone recently disputed this and said that all fluorescents are the same and need to be replaced every six months. Any input, such as a watts per gallon recommendation for power compact lighting? I have 384 watts on my 29 gallon reef (very crazy!). <Please read through the Marine Lighting sections, onto the CF FAQs posted on our site... starting here: http://wetwebmedia.com/lighting1MAR.htm> Last, would it be acceptable to have a saltwater tank (fish or reef) with live rock (1.5 + lbs/gallon), live sand (no more than 4" deep), a sump and a good protein skimmer as the filtration? <Sure> As a separate idea, would it be acceptable to have a reef with 2 pounds per gallon of live rock, 3" of live sand, and a canister filter (skimming from the surface) as the only filtration? <Could be made to work...> Thanks,
Ben
<You're welcome. Bob Fenner>