You need to stop worrying about the phosphates and start battling the algae instead. Phosphates are algae food, but if there is no algae, then your phosphate level doesn't matter! Your algae problems are probably because you simply haven't been consistent about keeping your chlorine levels high enough to compensate for your CYA level. If you will post a set of test results on your water, taken with a drop-based kit, we can help you get it cleared up....

Welcome to the forum!