Swimming Pool Shock Treatment — Calcium Hypochlorite (Super-Chlorination, Chlorine Gas Release, Fire Hazard, Chemical Incompatibility) — household safety profile
High riskCalcium hypochlorite (Ca(OCl)2, 'Cal-Hypo') pool shock treatment is a powerful oxidizing agent sold in granular form at 65-78% available chlorine concentration — used for weekly 'shocking' of swimming pools to destroy chloramines, algae, and organic contaminants by raising free chlorine to 10-30 ppm (versus normal maintenance levels of 1-3 ppm).
What is this product?
Calcium hypochlorite (Ca(OCl)2, 'Cal-Hypo') pool shock treatment is a powerful oxidizing agent sold in granular form at 65-78% available chlorine concentration — used for weekly 'shocking' of swimming pools to destroy chloramines, algae, and organic contaminants by raising free chlorine to 10-30 ppm (versus normal maintenance levels of 1-3 ppm). Cal-Hypo is one of the most hazardous consumer chemicals sold without restriction: it is a strong oxidizer (NFPA 3/0/1 OX) that can spontaneously ignite on contact with organic materials (oil, grease, wood, fabric, body fluids), reacts violently with acids (generating concentrated chlorine gas), absorbs atmospheric moisture to form hypochlorous acid with progressive decomposition, and has been responsible for numerous residential garage fires, chemical burn injuries, and fatal chlorine gas inhalation events. CPSC documented over 4,800 pool chemical-related injuries requiring emergency department treatment annually, with Cal-Hypo involved in the majority of serious events. The compound is classified as an oxidizer for shipping (UN 2880, Class 5.1) and must be stored separately from all other pool chemicals — cross-contamination between Cal-Hypo and trichloroisocyanuric acid (trichlor, another common pool sanitizer) has caused violent exothermic reactions and warehouse fires.
What's in it
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Chlorine Class Oxidizer
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