I have a new Intex Krystal Clear Sand Filter Pump for Above Ground Pools, 3000 GPH Pump Flow Rate, 110-120V with GFCI and when we started it up, back washed it, and then turned off the switched to rinse. When we turned it back on it just had a humming sound and was not running water through it. Any suggestions. We are first time pool owners and have a Bestway 9'x18' rectangular pool. The sand filter has the saltwater system attached to it.