Hi everyone. I'm new here. I am having an issue with my circulation and water level in the pump basket. When the pump turns on it primes for 1 minute (2785 RPM) and fills the pump basket up to the lid. During this time I can see a lot of water flow into the skimmer and the return jets are moving water aggressively. However, after about an hour with the pump on filter speed (1500 RPM) the level of water in the pump basket is half of what is was. I've also tried running at 1800 RPM. Also the skimmer is barely moving water and the flow from the returns is very weak. I've tried periodically purging air from the valve on the filter but I never get more than a quick hiss before a stream of water is coming out.
The pool is new for me but was built in 1991. It has one skimmer, one drain at the bottom, and two returns. The spa has one drain on the floor, one about 8 inches up on the wall, one return, and four jets. Any help would be appreciated.