how to stop a return line with a manifold from siphoning

[jrlg]

I have dual returns and I installed Wye check valves but installed below the manifold so if I am using a port from the manifold it wont stop because it has another route drain out. I fixed it by having the output of that return right below the water and with a power loss the sump holds what siphons down. But I want to have a better fail safe than letting that much water drain down, any suggestions?

 

[Lasse]

In the return line (if it ends up below the water surface) drill a small hole just at the surface. During running - you get a thin water spray out - during stop - air sucks in and stop the siphone

Sincerely Lasse.

 

[jrlg]

I did that on the return line inside the overflow but thinking of doing it to the lock line and having the hole point sideways so the water stays in the tank, my first hole had some pressure....

 

[jda]

That will work. Sometimes you need more than one if the hole is small... just test it and drill another if you need to.

Flapper valves (swing check valves) are OK, but they wear out and need replaced every few years... but they are reliable in the short term if you buy good ones.