To handle chloramine buildup and organic waste like sweat or sunscreen, you must perform a "shock" treatment. Shocking involves adding a concentrated dose of chemicals to oxidize the water and reset the free chlorine levels. This is typically done once a week, preferably at night, to prevent the sun’s UV rays from burning off the unstabilized chlorine. Managing Algae and Mineral Levels
CYA protects chlorine from being destroyed by sunlight. But too much CYA renders chlorine ineffective. pool chemical maintenance