Corrosionpedia explains Calcium hypochlorite
Calcium hypochlorite is a white or grayish white granular powdered solid with a pungent odor, which is corrosive and toxic. When calcium hypochlorite is dissolved in water, it gives off heat and nascent oxygen. When it reacts with organic substances and oils, it brings about combustion because of violent decomposition.
Calcium hypochlorite is more stable than sodium hypochlorite, and contains a higher chlorine concentration (30-75%). Like sodium hypochlorite, calcium hypochlorite also increases water pH, so it is advised to acidify the water during the disinfection process.
All forms of calcium hypochlorite contain insoluble residues that form sediments in the solution. It is important to eliminate the sediment before injecting the calcium hypochlorite solution into a treated water tank to avoid clogging.
Calcium hypochlorite is generally sold as 68% calcium hypochlorite combined with calcium chloride and other salts. It is used as a sanitizer in outdoor swimming pools. The calcium content hardens the water and tends to clog up filters; hence, some products containing calcium hypochlorite also contain anti-scaling agents.
Localized corrosion such as pitting and crevice corrosion of stainless steels can occur in the presence of calcium hypochlorite.
Calcium hypochlorite is best kept in a cool dry place away from any organic material. It is known to undergo self heating and rapid decomposition accompanied by the release of toxic chlorine gas, which is highly corrosiv