These are salts of hypochlorous acid and are formulated in several different grades and proprietary forms. Principally, they are composed of sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca(OCl)₂). Sodium and calcium hypochlorites are added to a industrial water system and function in much the same way as chlorine gas. When these two salts are added to the industrial water stream, they also 

ionize to different species depending on the pH of the system:

Ca(OCl)₂ + 2H₂O -> 2HOC1 + CaOH + H₂O
NaOCl + H₂O -> HOCl + NaOH 

Unlike chlorine gas which lowers pH, hypo-chlorite salts increase the pH of the water by adding calcium and hydroxide alkalinity as well as calcium and sodium ions. Because calcium can combine to form insoluble compounds with commonly occurring anions in water, the sodium form of hypochlorite is the preferred form.