How do I prevent and remove black algae in my pool?

Keep chlorine levels high (2-3 ppm) and brush the walls at least once a week with a stainless steel brush. Black algae has a waxy protective layer that chlorine alone can’t penetrate, so physical brushing is essential. Shock the pool weekly during warm months, and for existing spots, scrub hard and apply a chlorine tablet or concentrated shock directly. Prevention is key—don’t let chlorine drop, and never skip regular brushing.