Spa drains into pool with check valve flutter

Hi, I bought a new home with pool 5 years ago and things worked fine...until February. That's when I noticed that my spa was slowly draining into the pool when the pump was off. I soon traced the problem to the Pentair spa return check valve where the flap seal had deteriorated. I replaced the flap assembly with a new one from Pentair, but the problem only slowed down. I noticed that when the pump was off and the return valve was split 50/50 between pool and spa, the flap would pulsate...

Read more