About this item Fast-Acting Algae Control: Calcium Hypochlorite (Cal-Hypo) is an effective non-stabilized chlorine shock treatment, ideal for routine maintenance in your swimming pool Versatile Use: Suitable for above ground or in-ground swimming pools, spas, and hot tubs; Pre-dissolve or dilute to avoid bleaching the liner High Chlorine Content: 65% available chlorine, provides powerful sanitization for crystal-clear water Easy Application: Pre-dissolve or dilute to avoid bleaching swimming pool liners; Spread granules in the deepest part of the pool; Brush if needed Dosage: Use 1 Pound per 10,000 gallons weekly to maintain 5-10 ppm chlorine levels › See more product details