Ultima T.K.O. is a fast acting, quick-dissolving multi-purpose pool shock that sanitizes, clarifies, prevents algae and shock treats your pool. Customers love how quickly Ultima T.K.O. works. A 73% Cal Hypo pool shock, one easy-to-use 1 lb. pouch treats 15,000 gallons, destroying bacteria quicker than any other shock. T.K.O. shock provides powerful protection against stubborn algae blooms all season long, creating safe and clean pool water. Great for spring start-ups. 73% Calcium Hypochlorite.