Back pressure on filter

Mar 23, 2017
Hi. I have a back pressure problem. I recently sealed the connections just before the pump, and the cleaner went working normally. But I have back pressure when the pump is switched off. Pool service nearby advised it could be my filter sand. But I replaced the sand 2 months ago. Is there advice you can offer on the breather pipe in the filter? The cleaner is no longer working as it should. The diagnosis from the pool service centre is that the breather pipe was not placed back properly and therefore causing back pressure and finally causing the cleaner to default. Please help. Thanks.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Welcome to TFP... A Great resource for all your pool questions... :shark:

I assume that you believe that you have back pressure because the gauge on the filter has a reading when the pump is off...

If this is true, then the most likely problem is the gauge itself.

If water flows through your filter and into the pool when the pump is on, it would be impossible for pressure to remain in your filter.

If I have misunderstood the problem, please try to provide a little more detail about exactly what is happening..

Thanks for posting,

Jim R.


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
Welcome to TFP!

I think you are referring to air building up in the filter causing water to flow backwards when the pump shuts off. This is caused by a leak on the inlet side of the pump or a problem with water flow into the skimmer or vacuum hose.

Is your pump strainer basket full to the lid with no bubbles?


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
I think you are referring to air building up in the filter causing water to flow backwards when the pump shuts off.
I agree. You have a suction side leak. You didn't get all the air leaks out of the suction side.

With the pump on, air flows into the pump where it is forced into the filter. It resides in the top of the filter and the pump pressure keeps it in there. Pump off, the air in the top of the filter decompresses pushing water backwards out to the pool. The gauge should return to zero. find that leak and that backwards flow will stop.

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