5 Things to Know About Black Algae in Your Pool

Black algae grows in dead zones It forms in corners, behind ladders, on steps, or anywhere water barely moves. Poor circulation and low chlorine let it take hold.

Its waxy coating resists normal chlorine The algae has a protective outer layer that standard shock treatments cannot penetrate. You must brush the spots aggressively to break that coating.

You need high-dose shock or algaecide After brushing, hit the areas with a strong chlorine shock or a yellow/mustard algaecide. Run the filter 24/7 and brush daily for several days.

High phosphates feed it If black algae keeps returning even with proper chlorine levels, test for phosphates. A phosphate remover can starve the algae out.

Persistence is required Black algae is patient and will outlast a half-hearted effort. You must stay consistent with brushing and shocking until it is completely gone.