Hi everyone. I have a 27' AG pool and about 18000 gallons. My FC is 3 PH 7.5 TA 90 and cya about 35. I clean the pool of algae and it looks clean and clear but the next day when I run the filter I see algae on the bottom after about 1/2 hour. I have back flushed the filter several times and the sand is new 2 years ago (this is the 3rd year using it). It seems I have to clean it everyday and this was not the case in the past years. I would appreciate any suggestions. Do I need to SLAM? Weather here has been avg. of 85 F with sun and clouds, rain once in the last week.