When the pump turns on there is a LOT of air in the system blowing bubbles into the pool for a few seconds and it's loud. It primes ok and runs fine while the pump is on. After the pump turns off I can hear air going into the filter housing. If I open the pump basket lid, the water sits there - it doesn't rush out as it normally does. After the pump had been off a few hours I opened the filter housing and the water was about 6" from the top of the filters. I cleaned the large gasket and used gasket lube on it, and put it back together tightly, so I don't think it could be leaking there, but that didn't help air getting into the filter after the pump is off. I don't see any water leaking anywhere on the filter housing when the pump is on. I also cleaned and lubed the gasket on the pump basket. It seems to me that the air leak is either at the filter gasket or the filter valve on top of the housing but if there was a leak wouldn't I see water leaking out when the pump is running?