I know there are different schools of thought on sand changes. I know what has worked time after time based on first hand experience. If not changing the sand is the theory you'd prefer to follow, that's great.
Salt water chlorination is a process that uses dissolved salt as a store for the chlorination system. The chlorinator uses electrolysis to break down the salt (NaCl). The resulting chemical reaction eventually produces hypochlorous acid (HCIO), and sodium hypochlorite (NaClO), which are the sanitizing agents already commonly used in swimming pools.
Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor. HClO is an oxidizer, and as its sodium salt sodium hypochlorite, (NaClO), or its calcium salt calcium hypochlorite, (Ca(CIO)2) is used as a bleach, a deodorant, and a disinfectant.
Sodium hypochlorite is a chemical compound with the formula NaClO. Sodium hypochlorite solution, commonly known as bleach, is frequently used as a disinfectant or a bleaching agent.