Air check valve in DIY overflow???????????

[kdog]

I know there are two awesome DIY over flow sticky's on here BUT the AIR check valve is a bit of a mystery.

I understand the reason it should be there for start up but will it also automatically allow air that biulds up in the top of the overflow escape or do I need to manually/orally remove the air.

My sump runs for about five min. and then one of the overflows looses syphon. They are both identical to the ones in overflows 101. Don't get what I'm doing wrong!!!!

Lots of air slurping happening but i hope to minimize that as I get it running.

1 inch PVC overflows x2
900 mag drive (5ft of head)
NO check vlv (yet)

 

[Mavrick813]

It won't Automatically pull air out of the O/F unless you connect the line to something that will create a vacuum strong enough to open the Valve. I myself have a 5" piece of airline hanging off my check valves and every time I vacuum my gravel or start to hear a gurgle I suck the air out of the line.

If I ever get around to replace the check valve, I would just use a nipple and connect the line to a Maxijet 1200 and let that do the job for me.

 

[KaiserSousay]

Your overflows could be outrunning your pump.
Not enough return to keep both running at max flow.

 

[leather]

I don't use the check valve on any of my overflows. I never liked the idea of having them there to leak. I use a wet/dry shop vac to prime my overflows. I have never had a problem losing siphon, I have a 1 1/4 inch pvc, numerouse 3/4 and 1 inch (all different styles) and have lost no overflow capacity and have not had to restart any of the siphons once.

I would think your check valve is probably leaking air in, either change or plug to test.

 

[kdog]

I didn't have a check vlv in until after my post. After some more tuning I've got it I think. Biggest issue was not enough room between running and rest level in tank and two different heights on the overflows. Dropped over flows, levelled them and now the system is in balance and everything seems good. I have enough room in the sump for an outage and enough room in the tank for a syphon loss.