PVC OVERFLOW HELP WITH PICS

[Famos]

Hello everyone i just build a pvc overflow with 1" pvc pipe for my 90 gal tank at the moment i am using a pump that is pushing 258 gph. I read through all the PVC overflow thread to get a great understanding how to build and work one. Well here is the issue when i built the overflow i did like everyone stated and it worked fine when i tested it out in the bathtub, but when i put it in the tank a whole different story. i sucked all the air out and the water to start to siphon, but when i stop sucking for a few sec the water stop draining. when the water seem to come back up the tube that draining the water it appears to have bubble. What am i doing wrong please help!!!!!

 

[Burko]

"but when i put it in the tank a whole different story."

Clue No 1#

" i sucked all the air out and the water to start to siphon, but when i stop sucking for a few sec the water stop draining."

Its not a syphon, its supposed to stop.

"What am i doing wrong please help!!!!!"

its a bit hard to tell from the photos but...

The design looks fine so I would adjust the height of the inflows or increase the water level in the tank.

Once its primed you have to run the pump and watch and check the water level and adjust accordingly.

 

[Liquidplants]

My guess is the check valve is not holding... When you stop sucking air is returning into the pipe and breaking the siphon. Try taking the air line and putting it in a pump essentially creating constant sucking. Also it looks like the "high point" is on the other 90 elbow. A simple fix for that would be to put a spacer between the bottom of the PVC and the tank.

 

[ar0wan]

You've got the design correct
you're saying that when you plug the pump in
the tank fills to above the blue pipes and does not drain?
if so, there is still air remaining in the system
you have to prime the white uptube with water
prior to sucking out the air rite

 

[Juxtaroberto]

If there are bubbles coming out, then it's sucking in air from somewhere...

I'm assuming you sealed every joint with PVC glue? Are you sure you didn't put the air valve on backwards?

I see nothing wrong with your design...

 

[Liquidplants]

If you refer to his close up shot of the check valve it is in the right way. But I don't see any silicone or PVC glue remains. Has everything been sealed?

Also regarding my first post I think you may have a bubble of air that's never reaching the check valve.

ROUGHLY above that blue line could be filled with air and never removed by the check valve. So making sure it's level is key if you are having siphoning issues.
~LiquiD~

 

[Famos]

Thanks for the response. Yes the check is put in correctly with the arrow pointing up. So you are saying that on the top U that air cant not be sucked out???

 

[Famos]

I did prime it but when sucking all the air out for a few sec it drains the water then after about a minute the water fill back up in the blue tube,whenever filling you can see mini bubbles.

 

[ar0wan]

see mini bubbles where
I'm gonna need a video

IF you're getting a full syphon after priming
and the unit is fully draining
then the white uptube must be capped
it doesn't look like it from your pix
I don't think I understand the symptoms rite

 

[ar0wan]

... i sucked all the air out and the water to start to siphon, but when i stop sucking for a few sec the water stop draining...

The system is Designed to stop draining if the return pump is off
When you turn on the pump
Does the system restart once the water in the tank rises or does it overflow the tank?

... when the water seem to come back up the tube that draining the water it appears to have bubble. What am i doing wrong please help!!!!!

Are these bubbles in your sump?
This is not exactly desired but not uncommon either
that is what all the baffles are for in the sump
to prevent the micro bubbles from getting back to the tank