Looking for help -- had some brown algae after winter -- superchlorinated to like 22..gone for a few days -- then back again - Have been keeping chlorine at 10-20 -- brown algae reappears almost every day on vinyl liner for 2 weeks ---- the algaecides all say wait til chlorine is normal (1-4) -- so just brushing and adding chlorine has not been good enough. Numbers look ok & water is clear. Basic numbers -- pH 7.8, Chlorine 12, alkalinity 98, cya 55, calcium hardness 150, near zero phosphates, Iron & Copper at .1