return pipe not siphoning when pump turns off

[vr697getta]

i am setting up a new tank. this is the first time i ever had a tank with a built in overflow box and i am using loc line flow accelerators with an external pump. my question is that when i turn off the pump it doesn't create a siphon and drain water as low as the pipe is in the water like my current tank with an internal pump.

 

[mfinn]

I'm not sure what the problem is.
Are you worried because it doesn't?

 

[vr697getta]

not a problem i just didnt understand when it didnt happen

 

[Paul_N]

Do you have a pic of the return where it enters the tank? There has to be some kind of break or hole somewhere where the siphon is stopping.

 

[vr697getta]

i will take a pic or even a video both the returns are still under an inch of water and nothing is running into my sump. i have no idea whats going on lol.

 

[cloakerpoked]

A lot of tanks have a small hole drilled in the return line right in the middle of the 90 degree angle at the top of the standpipe. This is to prevent the backflow. Another possibility would be that somebody put a one way flow valve in the plumbing, but if you did it, then you would know if that was the case.

 

[vr697getta]

your first answer is right i just noticed it

 

[cloakerpoked]

Yeah, it's common practice, and especially in an overflow tank where you have the weir to dampen the sound, it's a clean place to put a break to prevent backflow. You don't lose as much as you'd expect as far as flow through the return line either.

 

[Paul_N]

YYou don't lose as much as you'd expect as far as flow through the return line either.

+1
I drilled three on mine right above my flow accelerator and didn't affect the flow.