When I turn off the pump, can hear water flowing out of the sand filter. The pump strainer basket stays primed until I turn the multi-port valve to backwash - then it drains quickly. Also, the little glass thing used to always have water in it but not now. Also have a few bubbles in the pump strainer basket and the return jets. Could it be the gasket in the multi-port valve? Thank you for any advice!
20K IG, Hayward Multi-port valve, sand filter, 1.5hp motor