My first post on here- it's great to find this forum. I have opened my pool for the fifth season and I have an ongoing air problem I've been unable to solve. It's an old pool (??? how old...), in ground, roughly 40,000 gallons, L-shaped, vinyl liner.
Anyway, the pump has always had air in it, which I have typically remedied by leaving the valve on top of the sand filter open a bit (hiss, all day long, and wasted water). On occasions when I don't leave the valve open, the air builds up until eventually the pump loses prime, and when I shut it off water explodes out the skimmers from the air pressure build up.
I've gathered that the problem is obviously on the intake side of the pump. I've done the following:
-replaced and lubed pump gasket
-replumbed lines from just above the ground to the pump, as advised by a pool technician
-slathered shaving cream on every PVC joint and on the pump, looking for a telltale sucking vortex (found none)
-caulked w/ silicone every PVC union as well as the pump connections, looking for a possible detection or temporary fix to the problem
So... I have read that the problem could be underground. (Is there really that much air underground? We're talking a lot of air. Hiss, spray, hiss spray, all day long from the filter top.)
Otherwise, perhaps the pump itself is sucking air between the motor and the pump? I've read that there's a gasket in there that can go bad but replacement seems pretty involved. I've considered replacing the entire pump just to rule it out. It's a big pump, 2 HP I think. Dates to 2003.
My choices now are, replace the pump or call in the pros... Any ideas would be welcome. I do think it's unlikely one of the obvious culprits, as I've been fiddling with it for four seasons now with lots of reading and trial and error.
thanks for any help-