Inground pebbletec ,10,000 gallons, Swg,sand filter 1hp pump. Just opened the pool. Still getting all the algae out so the water is silk very cloudy and blue listerinish. My problem is that my back pressure will raise to 30psi in about 30 minutes.i turn the pump off for 30 seconds then turn it on and my pressure drops to 12psi again. When the pressure is at 30psi the waterfall and the kreepy krawley stop working so I have to run outside all day to mess with the filter. I have back washed it 4 times in the past 3 days since opening it but I dont remember having to go through this last season. What could be the problem?