Cutrine Algaecide is designed to minimize the development of algae and other funguses on the surface of subsurface irrigated clay courts, including HydroCourts, Hydrogrids and Cal-Caps. Cutrine Algaeside should only be used in the water control boxes - do not apply directly to the court surface. Use 7 oz. for each control box every 4 months. Available in 1 Gallon size.