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

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

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

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>

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