5 Steps to Kill Black Algae in a Pool

Scrub daily with a stiff stainless steel brush Black algae has roots that dig into plaster or gunite, so brushing breaks its waxy coating and lets chlorine reach deeper.

Raise free chlorine to shock level for several days Check your pool’s cyanuric acid level and maintain chlorine at 10-20 ppm. A single shock treatment won’t cut it.

Run the filter 24/7 and backwash regularly Continuous filtration removes dead algae particles and keeps chlorine circulating effectively.

Apply granular shock directly on stubborn spots For algae that won’t budge, sprinkle pool shock right onto the spots or use a phosphate remover to starve it.

Skip algaecides and rely on chlorine and scrubbing Fancy algaecides are unnecessary. Chlorine and elbow grease are cheaper and more effective against black algae.