We have had a pool for about 3 yrs now and we just keep having trouble with it. Our pool is a 18x52above ground pool with a sand filter. Our problems are we seem to go from cloudy to green ...? We shock it clorine it and have used algeaside and clearifier. not in that order but we have been tring everything..Water is clear just smuge on bottom we vacum it and backwash we just changed the sand this yr.? Any Advice pls help. on ya and our clorine and ph in on right color with tester.