When pool starts, pressure strong but over the course of a few hours it drops to almost nothing. There are no air bubbles in the pump lid and it never loses its prime. If I turn it off and turn it back on, the pressure jumps back up. If I turn it up and open the air valve, it releases a little it of pressure. It will prime back up and start with full pressure.
Filters were fine but out of an abundance of caution I replaced them with brand new filters which did nothing to help. Any ideas??