Kills and prevents all pool algae (Kills green, mustard and black pool algae). Clear algae in 24 hours. Prevents & treat algae. Quick & effective - kills pool algae in 24 hours. Green. Mustard. Black. Non-foaming formula. For use in all pool types. Pool Types: Chlorine. Saltwater. Bromine. In-ground. Above-ground. Pop-up. Surface Types: Vinyl. Plaster. Aggregate. Gunite. Fiberglass. Concrete. Filter Types: D.E. Sand. Cartridge. Zeolite. Treats up to 25,00 gallons. Effective algaecide that kills all types of pool algae to quickly dean pools. Basic Green Algae: Most common type; free-floating, but may form on surfaces; can tint water green during blooms. Stubborn Mustard Algae: Yellowish dust/slime; fast-growing; clings to surfaces; needs algaecide - since it resists chlorine. Tough Black Algae: Black or green/blue spots; firmly attaches to surfaces with roots; forms protective crust. Clorox Pool: Free app. Water testing & solution center. Questions? Pool care tips? 1-800-Sos-Pool. cloroxpool.com. how2recycle.info.