Ball valve on overflow?

[nikirushka]

I've got DIY PVC overflows on 3 of my setups. Two work great. They hold their prime, so no issues if I turn the pump off, powercut, whatever. The third just will not hold it. I've no idea why but it's driving me crazy!

I may have the option of using a drilled overflow on that one IF I can get the plug out of it (I haven't done this because I already had everything I needed to make the overflow, but not to use that).

If I can't, I'd like to set up a simple one-pipe overflow with a ball valve, to take the place of the primed siphon of the PVC overflow. So if the power is off for any reason (or when I turn the pump off to do maintenance), it'll hold the siphon for when it restarts, in case I'm not home. It would also be useful for another setup that I really don't want to use the PVC design on (pain in the behind to set up with where it is).

How would I set up the pipe with the ball valve?

 

[nikirushka]

I mean a float valve, not a ball valve!

 

[DN328]

Can you take a picture of the overflow set-up. I'm not following how you have it set up using one overflow pipe. Did you really mean float valve?

 

[DThompson]

I've got DIY PVC overflows on 3 of my setups. Two work great. They hold their prime, so no issues if I turn the pump off, powercut, whatever. The third just will not hold it. I've no idea why but it's driving me crazy!

I had a similar problem on a saltwater tank years ago. my overflow box had 2 pipes and 1 was always full syphon and the other wouldn't stay at a full syphon all the time. I figured out that I didn't have enough flow to get the final pipe to a full syphon so I bought a bigger pump and that corrected the issue.