HELP!! PVC overflow problem

[ingrda]

I decided to retry making a sump for my new 180g tank. I drew up a plan with reference to uarujoey's videos on youtube and
this diagram and built it but I can't get it to prime and overflow all I can get is siphoning and once the water is no longer being taken down to the
sump due to the water level lowering, the pump then catches up but water is no longer taken back down to the sump by the overflow and will then
cause the tank to flood. I'm not sure what to do considering that overflow looks exactly like others that work with the exact same measurements. I think
its worth noting when I suck on the airline tubing and check value all I get is water and air mixed together and thus can't remove all the air.

 

[ruddybop]

Sounds like you have an air leak somewhere. Are all pieces of pvc glued together tight and is your one way valve sealed tight.
Another thing that happened to me was my one way valve was defective letting air back into the siphon causing it to stop.
Another problem I had was my silicone didn't hold the one way valve tight and sealed in the hole letting air in.
One more thing to look at if you have a cap on your breather tube on the back is there a breather hole in the center of it for air 1/8" or 3/16" hole.
If not it will suck all the water out of the siphon pulling air in.
If you suck on the hose and get air and water you have an air leak somewhere.....

 

[ingrda]

Sounds like you have an air leak somewhere. Are all pieces of pvc glued together tight and is your one way valve sealed tight.
Another thing that happened to me was my one way valve was defective letting air back into the siphon causing it to stop.
Another problem I had was my silicone didn't hold the one way valve tight and sealed in the hole letting air in.
One more thing to look at if you have a cap on your breather tube on the back is there a breather hole in the center of it for air 1/8" or 3/16" hole.
If not it will suck all the water out of the siphon pulling air in.
If you suck on the hose and get air and water you have an air leak somewhere.....

Ahh that explains it. I haven't sealed the pvc as I was just testing it. Thanks!