Filter Pump Half Full of Water an Hour After Backwashing

Jun 20, 2015
6
Massachusetts
So my filter pump basket becomes half full of air after about an hour of running the filter (the pressure also gets quite high). Once I backwash it, it runs fine (the basket is full of water) for about another hour. Then we repeat the process. The pool is dirty (green), but this means I backwash it like ten times a day (I've spent a lot of money on DE). I have also cleaned the filter, but nothing has changed.

I know that everyone says air in the pump basket means suction side leak, but if I switch to "recirculate" before backwashing, the pump basket becomes completely full of water and the returns blast out water very well.

Does the fact that my pump and filter run so well after backwashing indicate a different problem? Does the fact that it runs so well on "recirculate" mean there is an obvious spot where an air leak would be?
 
Welcome to TFP! Good to have you here :)

Sounds like there's a source of air on the suction side, but the flow is adequate with a clean filter (or on recirculate) to evacuate the bubbles from the pump strainer. If it were mine, I'd finish the SLAM and then evaluate the leak under more normal conditions. I'm assuming the pump is still adequately primed to keep the flow up.
 
People see it all different ways, but I always start with the easy stuff. First is the pump strainer lid, second is the drain plug. Remove and then clean the surfaces and threads. Anything on the mating surfaces (small bit of leaf, sand, etc.) might allow a leak. Remove the o-rings and make sure the o-rings are undamaged and the channels where they sit are clean. Then coat those two o-rings with silicone lube, re-fit the o-rings, and then replace the drain plug and pump strainer lid on the pump.

Next would be the union between pump and suction line, same as above.

If you have any pool valves on the suction lines, that might be the next place. I.e. anything above ground. Have a read through this article, and you'll get some other ideas relative to your system: Pool School - Suction Side Air Leaks
 
Alright one more thing before I search, I ran it on recirculate today and doing that had the same effect as backwashing the filter, the filter ran great (full basket) after like an hour of recirculating the water.

Basically, when the pump basket became half full of air I put it on recirculate instead of backwashing, the basket filled, ran it for an hour on recirculate, then switched to filter and the filter ran as if I had just backwashed it.

Is this a clue as to where the leak is?
 
I suppose the higher flow on recirculate could pull something tight against an o-ring, but I don't think it changes anything in terms of hunting for a suction leak.

Do you have any other suction sources? suction cleaner, spa, anything? Or is it just the skimmer and main drain? Are there extra skimmers? extra intakes for water features/slides?
 
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