Why does chlorine kill swimming pool algae?
Chlorine kills bacteria and other single-celled algae by a chemical action called oxidation, which is sort of like burning by acid. Most drinking water also has chlorine, for the same reason. And if you ever want to remove mildew from the bathroom walls, you can use a chlorine compound like Chlorox.
Our skin is tough enough that weak chlorine in water won’t hurt us, but you’ve probably noticed that in some swimming pools your eyes start to sting if you stay in too long. That’s the chlorine starting to “burn” them.
Water, including swimming pool water, contains disease germs. Chlorine is the most common sterilizer. Slight amounts of chlorine are used to kill germs, but are harmless to people. Where water is sediment-free, only one or two parts of chlorine may be added to 10 million parts of water (according to Compton’s Interactive Encyclopedia).