Pool Mate Black Algaecide is a 60% poly algaecide perfect for preventing algae growth and killing existing black, green and yellow/mustard algae. Pool Mate Black Algaecide also helps clear up cloudy water. It does not affect pH, won’t stain surfaces or leave residue. This product is non-foaming and non-metallic. Use weekly to prevent algae growth. Dosage: Use 4 oz. for every 10,000 gallons pool water for maintenance.