I have an above ground pool and have had the sand filter for 2 seasons (this is my 3rd). Last 2 years we ran Zeolite (sand alternative) in the filter and it worked like a dream; psi between 10 and 13 and backwashed whenever it hit 13. Great clarity and water balance both years. This year we opened and psi is running between 13 and 15. Backwashed A LOT and can't get the psi down. Replaced with new Zeolite. No leaks from hoses or tank. Motor seems in good condition. Nothing in the lower "skimmer thing", nothing in skimmer basket....Help!!! Columbia 12G tank Econo 3/4 HP motor