When algae starts getting out of hand, turn to the fast-acting Calcium Hypochlorite chlorine granules pool shock! The 68% Calcium Hypochlorite active ingredient is very effective at killing and deactivating harmful contaminants such as bacteria, algae and other microorganisms. With 65% minimum available chlorine, Cal-Hypo (Calcium Hypochlorite) will provide you with the sanitizing power you need to keep your swimming pool or spa water crystal clear and safe for your swimmers. Economically priced and packaged in 1lb bags to shock your pool or spa at your convenience. The non-stabilized formula is great for super shocking your water or everyday routine dosages, without the need to contain cyanuric acid. 68% Active Ingredient Calcium Hypochlorite pool shock treatment 1lb bags have 68% active ingredient to provide a strong, concentrated sanitization for your water. With 65% minimum available chlorine, In The Swim Calcium Hypochlorite will help maintain healthy and sanitary swimming pool water. Great For Pool and Spa Use Our 1lb bags of Calcium Hypochlorite make it easy for you to shock your pool or spa when you need to. In The Swim Cal-Hypo comes in 6 to 24 packs, for if you prefer shocking once a week or even once every day. Don't settle for anything less when looking for a pool shock to effectively treat pool problems like algae blooms and swimming accidents fast. As the chlorine dissolves in the water, it forms hypochlorous acid which is what kills and eradicates algae and bacteria. One pound of In The Swim Pool Shock will provide 5 - 10 ppm of free chlorine in a clean and balanced pool per 10,000 gallons of pool water. Pools with excessive debris, algae, suspended particles or heavy sunlight will need a proportionally higher dose of pool shock, to compensate for such factors. A double or triple dose is often required for poor water conditions such as spring openings, bacteria contamination, or severe algae