Any ideas what could be leaking or causing my what I believe my filter and return side draining down when the pump is off ? When ever my pump is down over night my strainer basket becomes empty just about to the bottom of it,about 6inches or so below the suction inlet piping (still water in the pump it seems but basket not full) and when the pump starts it ends up pushing whatever air is now in the piping and filter out the jets and of course the filter vent when I'm out there to vent it off?? Could it be my multiport valve possibly leaking off to backwash ? Is it beneficial to add a check valve or 2 when I re-pipe my pad this fall, after the filter or anywhere else in the system to prevent this ??