I have a pentair whisperflo 2hp to power a bubbler and waterfall for my pool. its separate from the filter lines and pump. My plumber flaked out for startup of my new pool it was in me. i got the filter going but cant get the feature pump. i took off the check valve and filled the return with hose water until it started overflowing. Then i put valve back on and fire up the pump. it runs for 10-15 seconds and the bubbler works. But then it seems it runs out of the water i filled up and i dont see any more water in the filter windows coming in. ive even tried putting check valve in open all the time but still nothing. any advice?