05 Oct 2012
Black algae is the dark horse of all algaes. It is the most difficult to eliminate and cure. It’s rarely a chemical problem. Unlike the other kinds of algae which require special chemicals, what you normally need to fight black algae is chlorine.
Black algae is really a surface condition. As your pool ages you’ll notice the smooth plaster you used to have becomes rougher. The rougher a plaster becomes, the more likely you’ll get black algae because this type of algae grows IN the plaster and not ON the plaster as other types of algae do. Think of black algae as a sign your pool is aging.
The easiest way to deal with black algae is also the most expensive way: Resurface your pool. Once your pool gets black algae you’ll be dealing with it until you resurface it. At some point in time you have to face this expense, but the good news is you can enjoy your pool without serious black algae and without resurfacing it for a long, long time.
To treat black algae do one of two things. Drop chlorine directly onto the spot or rub it on. This makes it retreat for several months at a time.