checkvalve to prevent drainage of tank

[SmartWrasse]

My LFS sold me a Valve to go in the plumbing of my 75g tank that will have a sump in cabinet made from a 30g glass tank. This valve is supposed to stop the tank from draining with a power outage.
Does this work?

[deReef]

It depends on what type of check valve that it is.But in general they do work but it will require maintenence.As they do get alot of junk built up in them.The one that I use is manuf. by a german company GF.Its only drawback is that it is clear an algae grows in it with in a month or two.I would be sure that during the install that it is able to be removed for cleaning and inspections.Nothing worse then thinking that it will work and finding out the hard way as you flood the place.I have my system so that if it were to fail the vaccum breaks will take care of the backfeed.An my sump is large enough to handle the return water in the event of a power failure etc.

[DgenR8]

Check valves and salt creep don't co-exist happily. As DJ said, there is also algae to deal with and don't forget, snails go everywhere they can fit. Not to mention, if there are any metal parts in that check valve, salt water will probably make short work of turning that metal into a toxin.
Set yourself up with a syphon break, you can clean it by just poking it with something every few days to insure it will work when you need it to, and no worry about metal parts.
We have enough things to worry about with our tanks, IMO, a check valve is an unnecessary source of possible problems.

[SmartWrasse]

The checkvalve is white PVC with a flap inside that you can move with a finger. It is labled kbi swing check. Dx: No metal seen

[Toutouche]

Well as with all threads on this site, you're going to get two sides of an opinion. I think, and I know alot of other people do also, that check valves are good,should be used, and should not get snails and such stuck in them when placed where they should be ( on the return side of the plumbing). Before a snail gets into the check valve it has already managed to get farther than it should have ( such as down the overflow, or even more important, has gone through your pump, and now either your pump is not working anymore, or you have snail puree). The check valve should be placed first thing inline right at the return from your pump, and as close as possible to it. Obviously it should have no metal parts in it. The best type, and only type that should be used is a swing flap type. These should have a kind of bump offset to one side of the body for the flap to swing into when the water forces it open, and out of the flowpath. It will have an arrow printed on the side, and make sure your water flow direction is following it. Have I forgotten anything?

[Toutouche]

AAh yes! I forgot one little thing. There are some available that are clear to see into. While they are good to see if the valve is moving properly, this type will grow algae in it, as will anything else that light can get into if light is present such as clear tubing. The other type that is usually a white plastic body does not let light get into it therefore you should not have the problem of algae growing, and hampering it's function.

[Duce]

I just drill a small hole in the return line below the water line.....the tank / return line will stop draining once the level reaches below the hole...no fancy valves, etc.

[Toutouche]

I have a question for all of you that use the small hole drilled in your return below the waterline. What happens to the water that is already in the return tube when you shut your pump off? Does the water in the line go down, and empty from in the tube into your sumps? If so what happens when you turn your pump back on? Does air come out till the line fills up with water from the pump, and sump again?

[mgbrown66]

I debated this very thing last week and decided to just drill a very small hole in my return LOC-Line (the Y type inside the tank, about 1 inch below the overflow.) I have plenty of room in my sump for the water level to go down about two inches in the tank.

When the return pump shuts off, the shipon kicks in and water comes barelling down into the sump until it hits that small hole. Then air gets sucked into the tube and the siphon breaks. I can see the siphon break, as bubbles come out of my return pump.

So to answer your question, all the water drains out of the return lines. When you turn your pump back on, the air in the return line will push up into the tank while the line fills up with water. This is not much air, and it's no big deal.