pbmarchkvalveFAQs

More FAQs about Marine System Plumbing Check-Valves, Back-Siphon Protectors

Don't rely on these absolutely for stopping water... provide for eventual failure... Where will the water go?

Make sure and plumb your check-valves in in the right direction...

http://www.wetwebmedia.com/ PondSubWebIndex/chkvalvpds.htm

Re: 220 gallon Overflows & Returns - 5/23/10
Thanks for the advise.
<Welcome.>
I decided to drill through the bottom of the tank. Now I have a question about my returns. I want to return two Mag 12 pumps separately, with 3/4" plumbing that will enter the bottom of my tank, run up through my sand,
then disburse with a 45 degree nozzle. I would have a gate valve and a check valve on each pump, but I'm worried the check valves might fail in a power loss and 220 gallons of water could drain down, through the returns,
overflowing my 75 gallon sump.
<Me too, they will fail, not if but when.>
Should I be concerned about the check valves failing?
<Yes.>
Is there a brand of check valves you recommend that can handle 220 gallons?
<I just would not. There is always something in a marine tank that will keep these from sealing in a pump outage. Even the slightest little leak will end in disaster should the power be off too long. I always try to place returns high up and just avoid the issue all together.>
Thanks,
Jon Weber
<Welcome, Scott V.>

Check Valves in Aquariums 5/13/09
Hello folks!
<Hello Frank.>
I had a quick question for you.
<Sure.>
I think I already know the answer but I wanted a second opinion. Anyways, I recently replaced some plumbing on a used 75 gallon setup that I bought off of craigslist. I basically replaced all the PVC as well as a cut off valve and a check valve.
<Okay.>
My question is concerning the check valve. I bought everything at Lowes and the only check valve they had was the type with a spring mechanism instead of the flapper type that was on the old plumbing. It just dawned on me that the spring will become corroded by the salt water and then the water will be constantly passing by a rusty piece of metal.
<It will in time, yes.>
Will this pollute my tank water in some way?
<Not to a noticeable extent.>
Should I replace it with something else?
<Yes! A straight piece of pipe!>
I have not put any livestock in the tank as of yet. Only live rock and sand. Do I need to change out the water also?
<Not due to this.>
That is all I need to know today and thanks again for all the knowledge you pass on to people like myself.
<Well, the bottom line is that any type of check valve cannot and should not be trusted to function in this application. Basically it is a matter of not if, but when the thing will get stuck open. A snail, algae, calcareous material, etc. will stick the thing open. The bottom line it is far better to have the extra volume in your sump to handle any siphon or drain down from the tank when the power is off.>
Frank Stubblefield
<Scott V.>

Potential Back-Siphon Problem! (Nah'¦I Don't Think So) -- 08/20/08 To WWM, <<Greetings Ed>> My name is Ed and I would like to thank you for all the information you provide. It has been a tremendous help. <<Always good to hear'¦from all the crew, you're quite welcome>> I am upgrading my 60 gal. reef tank to a custom built acrylic 120 gal. reef with a 30 gal. sump / refugium combo. <<Very nice>> The tank has two 1.5 inch drains and three 3/4 returns across the top of the back wall of the tank. <<Ah'¦this is excellent! So good NOT to hear the all too common 'single 1' drain' story>> I would like to add an additional return at the lower portion of the back wall in the center. <<I see'¦ Will you be doing this, or the tank fabricator? Some advice/precautions if doing it yourself for the first time. Be sure to use a 'bi-metal' hole saw'¦and use care not to overheat the cut'¦or inadvertently stopping the cut before removing the blade as there is a chance of 'sticking' the saw in the hole>> Here is what I propose to do: 1) Drill another 3/4 inch hole near the bottom center of the back wall below the existing hole near the top. <<Actually'¦ If you're planning to install a Â¾' bulkhead you will need to drill a hole about 1 5/8' in size. This can vary a bit depending on the particular bulkhead so be sure to check>> 2) Use SCH 40 PVC to plumb up to the upper hole first. The 3/4 inch pipe will be traveling vertically to a 90 deg. elbow. Then horizontally to the center hole. 3) At the upper center hole use a 90 deg. side out (a side out is a 90 deg. elbow with a third port coming out of the same corner generally used in tight corner applications where plumbing is coming down an inside corner of a cabinet and needs to go in two different directions). <<Understood>> 4) At the side out plumb back down to the new hole at the bottom back wall of the tank ending with a 90 deg. elbow to return flow to tank. <<I see'¦ I do think this configuration will result in the bulk of the flow exiting the top hole'¦with little being diverted to the bottom>> Both of the middle returns will be controlled by one main line. My concern is, if I lose power (which is not likely because I have a whole house back-up generator but I want to be triple safe) will the water siphon back into the sump? <<Unless the top hole becomes plugged this shouldn't be a problem. Once the water clears the top hole it should act as a siphon break. But like anything'¦do be sure to test this>> My assumption is that since both upper and lower drains are connected to the same line, once the water level gets below the first drain at the top that should create an air break and stop the siphon. <<Ah! Yes indeed>> Assuming I haven't completely confused you, does it matter what height I put the main feed to the two returns? <<I understand the two-hole configuration fine, but not sure I follow re your question about the 'main feed.' You state above the line would travel vertically to the upper hole and then make a 90-degree turn to the bulkhead>> I would like to have a ball valve for each return, <<A fine idea'¦to be able to temper flow on the output side of the pump(s). But I recommend you use 'gate-valves' as opposed to 'ball-valves' as these provide a more finite 'tuning' capability>> but to do that the main feed needs to be across the middle of the tank with a tee to feed the upper and lower returns. <<Oh'¦okay'¦this should work better than what I originally envisioned re diverting adequate flow to each return>> Thank you for your help, Ed <<Happy to assist'¦ And do write me back if you need/wish to discuss any of this further. Regards, EricR>>

Re: Potential Back-Siphon Problem! (Nah'¦I Don't Think So) -- 09/01/08 Just an update on the siphon issue. <<Great!>> I plumbed the tank with the 3/4 inch pipe coming up to midpoint of the tank. At that point there is a 90 deg. elbow taking the pipe horizontally to a tee. One line going to the top of the tank and one to the bottom with a ball valve on each. Each line ending with another 90 deg. elbow into the bulkhead. <<Okay>> I filled the tank for the leak test and turned off the pump. As I feared, even after the water level cleared the upper return, I still had a siphon problem with the lower return. <<Mmm, I see'¦this is likely due to the pipe only 'coming up to midpoint of the tank' thus keeping the 'juncture' leading to the bottom bulkhead well below the water line. Perhaps if you run the return line to the 'top' of the tank and use the 90-degree side-out fitting to feed the bottom bulkhead; as you described in your first email, this will be sufficient to break the siphon>> Apparently, there is enough water pressure to force the water to go up the pipe and flood the sump! <<So it seems>> Help! <<It would help greatly to see pictures/diagrams of the plumbing arrangement>> If I re-plumb the line to go all the way to the top of the tank and work its way back down to the two bulkheads, will I have the same issue? <<Is worth the try, don't you think? Bringing the return line up to/above the top bulkhead should facilitate with breaking the siphon when the water level falls to/falls below the top bulkhead>> I am looking forward to any suggestions, since I already have the tank drilled. Thanks, Ed <<Try rerunning/experimenting with the routing of the return line and the positions of the fittings as this is the easiest and best option at this stage. Worse-case, you can always 'plug' the bottom bulkhead'¦or'¦a better option would be to use it to feed a 'true' closed-loop. Good luck and please do keep me posted/come back to discuss options. Regards, EricR>>

R2: Potential Back-Siphon Problem! (Nah'¦I Don't Think So) -- 09/08/08 Success! Eric, my siphon problem has been solved. <<Ah, very good to hear my friend! And do please accept my apologies for the tardy reply. I was away at MACNA where I attended some excellent lectures, met up/got reacquainted with some good friends, and killed a few billion brain cells while hanging out with Bob. I guess one of these days I'm going to have to break down and get me a laptop to take on these and other adventures to help keep up with queries>> After a lot of staring at my failed set up, I came up with a new configuration for the return. <<Do tell'¦>> The new design eliminated the 90 deg. side out from my first configuration and the flow problems you suggested may occur. <<Excellent!>> I don't have the resources to give you a diagram so I will do my best to describe the plumbing. <<Very good>> The 3/4 inch return pipe goes vertically from the pump to the top of the tank to a 90 degree elbow. The line then travels horizontally to a tee. One side keeps going horizontally to a valve and then to a 90 deg. elbow into the tank. The other part of the tee travels back down to the level of the lower bulkhead to a 90 deg. elbow. At the elbow the pipe travels horizontally to another valve and then to the final 90 deg. elbow and into the tank. With this design I am able to regulate flow to each return accordingly. <<Sounds fine'¦ And hopefully your pump is large enough to still produce some useful flow against all that headloss'¦though easy enough to upsize if need be>> More importantly, when the pump was turned off, I was able to break siphon to both returns. <<Ah yes'¦just as we surmised in our last exchange. I'm happy to hear it worked for you!>> Hurray! <<Indeed!>> Thank you for all of your help, Ed <<The pleasure is mine'¦thank you for all the feedback. The back-and-forth exchange does much toward helping others who will read this down the line to learn what does/does not work. Cheers mate, Eric Russell>>

Emergency Check Valve failed... New tank? 7/7/08 I had a 90 gallon reef aquarium running fine for 5 years. The power went out, check valve didn't work the tank back siphoned into sump and drained all but 4 inches of water. <Very sorry to hear about this, check valves will fail, you are the fourth instance I have heard of this week alone!> I saved fish and corals they are now in a 24 gallon nano reef set up. <Yikes!! I hope it is not too many fish/corals, and not too large.> I used the same water as in the tank, but added new live sand and TLC to help cycle. I am getting an Oceanic 144 gallon half circle tank in a couple of days. <Nice.> I need to have it running like my old reef tank without going through the full 6 week cycle. I was thinking adding live sand and TLC with new water along with my live rock. Is this possible to complete in a short time? <Yes, it is possible, if nothing else your livestock will fair better in the larger tank anyway, more stability and dilution of pollutants. Do not add any new, possibly uncured rock for a while. Your sand can be reused if either kept alive or washed.> I don't know how long my fish and coral can last in the nano cube. <Likely not too long coming from such a well established 90 gallon, I am surprised it all fit! For the time being I would consider refilling the 90 and putting the livestock back in it (if the tank/stand are not damaged). All you have right now is a holding tank, might as well make it bigger if you can. Good luck, Scott V.>

Sump/Overflow Question'¦Best Way To Temper Flow? -- 09/01/07 Good morning all, <<Greetings Daryl'¦evening now>> Thank you again for the world of info on your website. <<A collaborative effort'¦we hope you find it useful>> I hope this finds you well. <<Doing fine, thank you>> I recently moved my 55-gallon FOWLR to a 75-gallon aquarium with an overflow. In the 55 I was using a canister filter and skimmer; the 75 is my first venture with a sump. <<A worthwhile change/upgrade>> I am currently using my CPR hang-on skimmer with the 75, planning on eventually using a skimmer in the sump instead. <<Ah good'¦perhaps one from my current fave, Euro-Reef>> The sump is a Megaflow 2, which is sized for a 75-gallon aquarium; my return pump is rated at 950 gal/hr. Sump intake is through a 1 1/4" hose and is output through a 3/4" hose connected to the pump (not split). My question is this: The volume of water coming into the sump tends to overflow the prefilter pad daily; I rinse or change the pad, which quiets things down for awhile, but in about 24 hours I am back to overflowing the pad. <<Perhaps a coarser pad would not clog to quickly>> The water in the overflow bubble chamber is approximately 3/4" above the prefilter tray, which seems (to me) a bit much. <<Why, what problem is this causing?>> What is the best way to lessen the water coming in to the sump? <<Reduce the volume of water being pumped up to the tank>> Am I better off installing a valve on the intake to lessen the flow into the sump, or would I be better off splitting the return to the tank? <<Don't place a valve on the drain line, but rather, install a 'gate-valve' on the 'output' side of the pump to temper flow as needed>> My guess is that splitting the return would be a better option, as I would also increase water movement with a second output, but I would very much appreciate your opinion. <<You can split the return if you wish'¦but do still install the valve for best 'control' of the flow rate>> Thank you in advance for all your help. <<Happy to assist>> All good wishes, Daryl <<And to you in kind. EricR>>

Re: Sump/Overflow Question'¦Best Way To Temper Flow? -- 09/03/07 Sorry to bother again...very quick follow up: <<Hey Daryl! No bother mate>> I have a check-valve on the output of my pump. <<Is a mistake to use/rely on these devices in my opinion. Much better to design/install plumbing such that the sump will handle all transient water volume. The check-valve imparts significant resistance requiring a larger pump (and associated cost/energy consumption) than normal, and will most assuredly fail at some point>> If I install a gate-valve, should it go inline before or after the check valve? I would assume the gate-valve would come first, followed by the check-valve... <<This might be fine (If you are determined to keep the check-valve). Though depending on the size/type of valve and how much you need to reduce flow, you may find that the valve stops all flow before the desired rate is reached if the gate-valve is installed first. This is probably of little concern, but a bit of experimentation will tell>> Thank you again, and all good wishes, Daryl <<Happy to help. EricR>>

Check Valves... SW Ap. - 03/25/07 Hi Bob, Last email you answered was regarding setting up a business with a partner. I don't have a partner, but I am working with a friend through his retail shop. Anyway, my question to you is - what are your feelings regarding check valves? <Mmmm, have their place, utility...> I have recently put up a 175 gal with an external Dart sequence 38. I have restructured the returns so that both holes in the overflow box are used for overflow; therefore I added 4 check valves on the 4 return pipes. I am catching a lot of flack from the reef club telling me they will malfunction and cause major problems; however, my friend who I am working with has been installing them on large customer tanks for at least 15 years with no failures. What is your take? <Are these valves discharging below... much below the water line? If not, I don't think this is an issue... If your sump will handle the transit volume... the water in play... as if the check valves weren't present. BobF> Thanks, Vicki

Check Valve <Hello> I purchased a check valve from an online aquatic retailer for my saltwater setup. The one I received is a spring type. I inquired into it's safety due to it's application and I was told it would be fine since the insides were stainless steel. I'm looking for a second opinion, any words of wisdom to pass along would be greatly appreciated. Nick <Nick, stainless steel is a great metal for freshwater but it does corrode faster in saltwater, and in a captive system I would look for either a titanium spring model or find a sealed check valve that immerses the stainless steel springs in oil. There are several different ways to make them, and most industrial supply stores will have such things if the LFS in your area do not have them. If you must use the check valve you have now please watch it closely as over a few months or weeks depending on the metal, it may rust and will start killing fish and corals.> <Justin (Jager)>

Plumbing siphon break Dear WWM crew. <Stepahn> I was doing my finishing touches on my plumbing. I have two manifolds each with its own pump that are hooked up in the sump below the tank. <The pumps themselves are there I take it, not the manifolds> I ran into a problem with one of the manifold. This one is a loop of flexible PVC and six tee's tied to six bulkheads. These bulkheads are all drilled thru the back wall of the tank. My water input is situated near the bottom of the PVC loop with a union. I have an additional tee with a fitting that is just above to water to break the siphon. <Oh oh...> I turned on the pump and water seem to be running fine thru the manifold until I turned the pump off. I heard a expected sucking noise from the siphon followed by a gushing water sound pushing back into the pump. Water in the sump started to rise quickly until I was able to stop the flow with the ball valve. <Yikes> And for my questions: Is the location of the union connection (below the water level) in the wrong location? Should it be at the top? <Yes... needs to be above the upper tank water level, or at least at the absolute lowest level you want the upper tank to drain to> I am saying that because the other manifold is hooked up with a union at top and that siphon break works. I was thinking maybe I should create a close circulation of loop instead. How such a thing be hooked up? My guess is to giving up the stand pipe in the overflow chamber, connecting the bottom bulkhead to pump's intake? <This is one way> If so, wouldn't it suck all the water out of the overflow considering that my pump is 2100 gal./hr. <No... will only pump/suck the water that is higher/over the overflow> I' not sure what other aquarist hook up their closed loops but I don't think a bulkhead on the back wall of the tank would be the answer here. I am afraid with this way the animals would get stuck on the screen of the intake. <Me too... a reason for having more than one overflow, using good screens, hiding these pieces of pipe behind structure (rock et al.)> Thanks for the fatherly advise as always. Sincerely Stepahn Gaudrau <Do you have a drawing, clear photo of what you have, and what you hope to do? Please send along if so. Bob Fenner>

Re: siphon break This raises other questions. If I were to use the 2100 gal./hr to hook up a closed loop, does that diminish the turnover rate? <Yes, to some extent> Originally two pumps were at the sump level. <Mmm, for the sake of clarity, completeness here, it only matters what the respective water levels are in the tanks> The tank is 175gal. sump/refugium is 75 gal. and external upstream refugium is 45 gal. This is almost 300 gal of total water. Am I turning this 300 water 20x or is it just the tank itself? <For the tank's consideration, just itself... for other containers, each one respectively> that would mean pump capable of pushing 6300 gal.? I am afraid to eliminate a valuable overflow drain. Can one still have the stand pipe plus an intake for the pump? Are there other ways to hook up a closed loop system? <There are... From what I understand from your messages, I would not abandon the current bulkhead/through-puts (and have a hole drilled, fitted for an overflow standpipe), BUT rig an external rigid pipe manifold/collective drain from them (outside the tank) with one or more tee risers as siphon breaks... with one (or two) drain lines going from this overflow manifold to the lower tank... and just some (one or two capacities/hour of the water from the lowermost tank/sump to the upstream refugium. Does this make sense? Bob Fenner>

Metal Inside Check Valve Hi, I'm planning on using a check valve for my return line from the sump to the main tank. When I got the check valve home, I noticed that it has a piece of metal and a metal screw inside of it. Is this safe to use? Much thanks for a fantastic web-site! Greg < I wouldn't use this just to be safe. There are check valves made for this application, check our sponsors for these. Cody>

Re: Metal Inside Check Valve Hi Thanks for the great advice. One last question :) I woke up this morning to find a piece of hardened silicone sealant floating in my tank. I did some PVC work for my sump and used silicone sealant, but I let it cure for 24 hours before using it. Is this something I should be concerned with? Do you think my water in contaminated? Regards, Greg <I wouldn't worry about it. Cody>

Anti siphon... Bob- I will be re-plumbing my tank soon and recall reading about a way to keep the tank from siphoning the water back in to the sump, without the use of a check valve, should there be a power outage. I think it involved drilling a small hole somewhere but, that's about all I can remember. Can you help? Thanks. Andy <There are a few ways this can be done... If you're pretty sure you're not going to regret drilling/fitting the tank (rather than fitting an over-flow box like the ones made by CPR (Link below), then I would cut (or have cut if a glass tank) a circular opening, fitted on both sides with a gasket, a bit of silicone sealer (100% designated, like the ones sold for aquarium use) smeared on the gaskets, as big a through hull fitting as you think you'll ever need/want... (at least 1 1/2" if not 2"...) for the overflow... a small section of pipe attached to the back side throat of the thru hull and then a "Tee" fitted vertically, connecting the through hull and the drop section of plumbing to your sump... with the up part of the Tee as an aspirator (to break the siphon action)... and another tee or street "El" in the tank with a "hand pushed in" (i.e. not solvented or threaded) piece of pipe going to the bottom (screened some how)... if a Tee inside with the upper part of the tee acting as an alternate over flow (lest the bottom intake get clogged... Anyone capable of drawing such things on these devices? This is the best of many possibilities... Would attach, do advise the use of an alternate overflow outlet... either another cut through fitting or an overflow box. CPR, Oz Reef (great site for DIY aquarists) links can be found on the pages of the same name on the site: www.WetWebMedia.com Bob Fenner>

New Pump Plumbing Question Hi Bob, I've had a frustrating day (and evening) installing a new pump, and I desperately could use some wise guidance. Here's the deal: I have a Mag 12 pump on my 300 gallon reef tank. The flow rate for the tank is obviously too low, so I went ahead a picked up an Iwaki pump. (MD100RLT). I hooked up the Iwaki, and I find the flow rate to be ridiculously low . . . and I mean looooooow . . . as in my dog drinks water faster. So, I hooked the Mag back up in the interim, and I am seeking a little guidance. Maybe you know the answer right off? ;-) <Mmm, don't even know the questions yet> Here is the plumbing situation: The Mag 12 has 3/4" fittings. It is immersed in my sump, sucks water up, pushes it through a "T" connector, and pumps the water up each side of the tank. It uses 1" OD / 3/4" ID tubing. The flow rate, while certainly not optimal, is not all that bad. <Okay> The Iwaki has 1" fittings. Being an outside pump, I added a 1" bulkhead <Outside diameter I'll trust/assume... one does NOT want to bush down intake fittings> fitting in the sump. I made sure not to reduce the 1" inflow into the pump, as I've heard doing so can give flow-rate problems. <Oh! Yes> It then pumps through a 1" check valve. <Why a check valve here? Your sump won't accommodate the volume that might drain back if the pump, power failed? What type of check valve? Spring, ball types are trouble (compared to swing)... some coverage on these on WWM, under pond plumbing.> I then use a constrictor to reduce to use the already-there-for-the-Mag 1" OD / 3/4" ID tubing. I am thinking perhaps I should just rip out the small tubing and keep the whole setup from Iwaki-to-tank at 1". I don't want to rip out the old stuff unless I know that is the problem, however. <... ah... and all this on a three hundred gallon system...> Bob, what's my problem? Why is that Iwaki pumping so slooooooooooooooooow? <A few things... but most all having to do with the plumbing arrangement... "T's" are trouble with pumps that are engineered for flow versus pressure... as are restrictions/induced drag in small diameter conduits... But, skipping ahead... do re-design your plumbing and consider getting/using a direct drive pump... like an RK2 product instead... Maybe make up a diagram of what you have in mind plumbing wise, and we'll chat this up. Bob Fenner> Thanks a million! Dale.

Re: New Pump Plumbing Question Bob, Thanks for the advice . . . It was the check valve. Dale.
<Ah... suspected as much. Bob Fenner>

Please visit our Sponsors