I'm having an issue that I can't seem to figure out. For the past two nights, my pump and filter will be running fine. However when I get up in the morning, everything is running however no water is being returned into the pool. The pump will still be running and the basket is full of water (no air) so I don't understand. I turn the filter to backwash and allow it to cycle a few minutes then when switched back to filter, everything begins to work fine.