well, I think we've tried checking all the obvious air leak candidates (pump basket, skimmer basket, copper/PVC joint, PVC pipe to pump basket, am I forgetting anything - previous thread here http://www.troublefreepool.com/air-l...te-t25192.html)
When the pump is off, the water level in the pump basket is stable, so if I bleed the air and leave the pump off overnight, the water level doesn't drop noticeably. I don't notice the water level dropping while the pump is running (although I can't say I've been watching it closely), but when I check on it after the filter has finished running, the water level has dropped to at least below the level where the PVC pipe enters the basket case (basket case being what I feel like after dealing with this ). This evening hubby checked it and when he opened the basket, he had to add about 7-8 gallons of water to get the basket filled again (he said the water was running back towards the skimmer as he filled it, so he's guessing the 7-8 gallons is the capacity of the pipe running back to the skimmer)
We're at a loss for ideas now - any suggestions?