4 Steps to Eliminate Black Algae in a Pool

Brush aggressively with a stiff brush Black algae grows roots into plaster or vinyl. Use a stainless steel or nylon brush to physically disrupt those roots. The surface may look clean after brushing, but the roots remain until you break them up.

Apply a copper-based algaecide Regular chlorine alone will not kill black algae. After brushing, treat the area with a copper algaecide to target the algae at the root.

Superchlorinate and maintain high chlorine Keep chlorine levels high for several days after treatment. This sustained shock helps finish off the algae as you continue brushing daily.

Repeat brushing daily for up to a week Black algae is stubborn and requires persistence. Brush the affected spots every day until the algae is completely gone. Prevention is easier—balance chlorine and pH, brush weekly, and attack any black spot immediately.