Sump issue

[Thinbloke170]

I have recently acquired a 700 litre tank with sump.
The issue I’m having is one of the returns gets an airlock when the pump is switched off.
When the pump is switched back on, due to the airlock in one of the returns the tank fills up and would eventually overflow.
Is it a simple question of drilling a small hole in the top of the return to allow the air to escape or is there something else I can do.

 

[Andy Sager]

I have recently acquired a 700 litre tank with sump.
The issue I’m having is one of the returns gets an airlock when the pump is switched off.
When the pump is switched back on, due to the airlock in one of the returns the tank fills up and would eventually overflow.
Is it a simple question of drilling a small hole in the top of the return to allow the air to escape or is there something else I can do.

I'd try inserting a check valve into the line to prevent any kind of air lock. But the real question is how is air getting into the plumbing to create an air lock?

 

[Thinbloke170]

I'd try inserting a check valve into the line to prevent any kind of air lock. But the real question is how is air getting into the plumbing to create an air lock?

Hi Andy
Thanks for your reply.
If the pump is switched off the water drains back to the sump, in doing so the return pipes end up above water line so air can then enter.
If these pipes were any lower in the water the sump would overflow.

 

[Andy Sager]

Hi Andy
Thanks for your reply.
If the pump is switched off the water drains back to the sump, in doing so the return pipes end up above water line so air can then enter.
If these pipes were any lower in the water the sump would overflow.

Got it. If you install a check valve into the line, the water can't go back into the sump. Depending on what size your line is, you may need to improvise with a larger PVC valve with barbed nipples but it will be worth it to not have the water going back into the sump.