Hello, I am new to the forum. I have an inground pool with a Hayward variable speed pump, a pentair filter and a solar heating system. I am having an issue with the solar heating. The pump will not prime when the solar is turned on. If I close that valve and "turn off" the solar the pump primes right away. If I then open the solar valve after the pump is primed it will purge the air out of the system and work. I just cleaned my filter. It seems when the water drains the next day it just cant prime with the solar on. It worked fine last season so I'm pretty stumped. Any suggestions?? Thanks!!