First Choice Black Out Shock Granular delivers 90% available chlorine in a stabilized trichlor formula, quickly raising chlorine levels, destroying organic contaminants, controlling algae, and restoring clear pool water. The stabilized formula offers improved sunlight protection, helping the sanitizing power last longer than unstabilized chlorine products.

Packaged in a 50 lb pail, this bulk chlorine treatment is ideal for pool service professionals, commercial facilities, property managers, and dedicated pool owners who need a dependable solution for routine sanitation, algae control, and corrective water treatment.

• High-strength granular chlorine treatment
• 90% available chlorine
• Stabilized trichlor formula provides improved sunlight protection
• Quickly increases chlorine levels and helps kill bacteria while controlling algae
• Helps eliminate organic contaminants and improves cloudy or dull water
• Suitable for residential and commercial pools
• Granular formula allows controlled application
• Bulk 50 lb pail reduces restocking frequency

• Always test the pool water before adding chemicals
• Maintain chlorine, pH, total alkalinity, calcium hardness, and cyanuric acid within ranges stated on the label
• Apply this product only according to the instructions printed on the container; dosage varies by pool volume, current chlorine level, water condition, algae growth, weather, and swimmer load
• Do not add this product through the skimmer unless the label specifically permits it
• Never mix with calcium hypochlorite, liquid chlorine, acids, ammonia, or any other pool chemical
• Important Water-Chemistry Notice: This stabilized trichlor may increase the pool's cyanuric acid level with continued use