Check Those Check Valves!

[RMS18]

As I'm home in NJ sitting in this blizzard I decided to do a water change. When I shut my return pump off I noticed the sump water level kept rising. Immediately closed ball valve so I could figure out what was going on. I saw my check valve wasn't closing.

If I was to lose power my sump would have over flowed and flooded before I would have noticed.

So gental reminder to clean those check / Y valves!

 

[Greybeard]

I don't use them. Now you know why... and without the flooded floor that taught me the lesson!

The least little bit of sand or grime, and they don't work.

 

[RMS18]

I don't use them. Now you know why... and without the flooded floor that taught me the lesson!

The least little bit of sand or grime, and they don't work.

What prevents back syphon when your pump is off?

 

[Greybeard]

What prevents back syphon when your pump is off?

I drilled a hole, just under normal water level, in my two return lines, and sized my sump appropriately, so that it has the capacity to hold what water does flow back into it when the power is out. Water level in my 140g tank drops about an inch and a half, water level in my 55g sump with the return pumps powered down is about 3 inches below the rim.

Actually, I bought 'siphon stopper' returns when I set this system up, but I don't recommend them. Expensive, and not any better than you could piece together from a few PCV fittings. They generated micro bubbles in my tank. I still use them, but cut the splash guards off, plugged the original vents, which were above water level, and re-drilled a 1/16" hole, about 3/4" below normal water level.

Original pic, before I altered them:

That pic shows the H2Overflows from the same company... Those I do like, and recommend. Works great, low profile, easy to maintain, and when set up right, completely silent.

 

[Susan Edwards]

I've also read that you shouldn't have your returns to far into the water column--just below the surface--that way only that amt of water can back siphon down, used also with that siphon breaking hole. Returns are just to return water. For flow, wavemakers and powerheads are used. I'll be setting up my first sump and overflow system soon and this is what I plan. Will prob. use a check valve for redundancy but mainly it will be placement of returns

 

[kschweer]

I agree with those saying do not rely on check valves. They can and will fail. Small drilled holes are also a bit “iffy” in my opinion. They can become clogged easily and also fail. By placing the lock line on your return just below the water surface you can stop back siphoning. It will only be able to back siphon a small amount back into the sump.

 

[ca1ore]

YUP, don't clean 'em ...... remove 'em! My view is that if you 'need' one your plumbing is done wrong.

 

[Greybeard]

Small drilled holes are also a bit “iffy” in my opinion. They can become clogged easily and also fail.

Yes, they can. Inspection and cleaning these holes is on my weekly maintenance list. With mine, there's enough flow exiting the holes that they stay pretty clear, but yes, I look at them every week. If they did become clogged, it would siphon nearly half of my 140g display into the floor of my sump room. Not a pretty picture. I've never had it happen, but it's near the top of my nightmare list (right under a busted lower seal in the display tank!).

 

[RMS18]

YUP, don't clean 'em ...... remove 'em! My view is that if you 'need' one your plumbing is done wrong.

My lfs drilled and built my tank and plumbing. Well nothing I can do about it now haha I'll just do a weekly inspection!

I do like the idea of 2 return pumps though not sure if I have room in my sump for that.

 

[Greybeard]

I do like the idea of 2 return pumps though not sure if I have room in my sump for that.

I saw BRS recommend this setup. I think there may be a flaw in the plan.

Ok, picture working overflow, 2 pumps, each with their own return line.

Pump 1 fails.

Pump 2 is pumping half as much as both were pumping, pump 1 now goes into SIPHON mode, pulling water back out of the tank, into the return compartment. A normal siphon break isn't going to work, as pump 2 is going to keep display water levels above any siphon break.

Question: Is pump 2 going to push enough water to keep the overflow operational? Or is pump 2's siphon going to be the only return path under these conditions?

Only way I know of to find out would be to test it. I suppose you could do an anti back flow valve, but hey, isn't that what we were talking about as being unreliable?

I'm just not so certain this would be a good thing. With a single return, when it fails, tank to sump flow stops, but my wavemakers will keep the tank stirred... Sump level will rise, and that will cause my ATO over-fill alarm to go off, hopefully alerting me to a problem.

 

[ca1ore]

The best, most foolproof approach is to not submerge the return outlet more than 1/2" in the display. Check valves fail, and are a drag on flow; siphon holes can clog or be covered by a snail (personal experience). I don't personally like the idea of dual pumps; better in my view to just select one with a long track record of reliability (excludes most DC pumps).

 

[RMS18]

I saw BRS recommend this setup. I think there may be a flaw in the plan.

Ok, picture working overflow, 2 pumps, each with their own return line.

Pump 1 fails.

Pump 2 is pumping half as much as both were pumping, pump 1 now goes into SIPHON mode, pulling water back out of the tank, into the return compartment. A normal siphon break isn't going to work, as pump 2 is going to keep display water levels above any siphon break.

Question: Is pump 2 going to push enough water to keep the overflow operational? Or is pump 2's siphon going to be the only return path under these conditions?

Only way I know of to find out would be to test it. I suppose you could do an anti back flow valve, but hey, isn't that what we were talking about as being unreliable?

I'm just not so certain this would be a good thing. With a single return, when it fails, tank to sump flow stops, but my wavemakers will keep the tank stirred... Sump level will rise, and that will cause my ATO over-fill alarm to go off, hopefully alerting me to a problem.

I was thinking 2 pumps on the same return lines... y pipe them together.