Fish1414

OP here....pump now works normal as long as I lave it running in high mode. If I turn it off or to low mode the water leaves the pump. Turned it off last night and this morning the spa was more than 1/2 empty (pool water enters spa first then spills over into the pool)

OP here.....I have 3 skimmers and the main drain coming into the pump (plus the spa side, but there is no issue there). If I set it in skimmer 1 only, the water primes and flows and everything is ok. If I set it on any other skimmer or the main drain.....or if I even add another skimmer or main drain to the action, the water flow disappears and the pump runs dry. I'm thinking this is some kind of clog and not an air leak??

When running in pool filter high or low mode (2 speed pump) the pump basket won't maintain a prime. Switch to spa and the water flows and prime is held. If the issue was right there at the union leading into the pump gasket, then I would not think the spa side would work either? Any suggestions?