What is combined chlorine?

“Undesirable, foul-smelling, body irritating compounds formed when insufficient levels of free available chlorine react with ammonia and other nitogren-containing compounds (swimmer and bather waste, fertilizer, perspiration, urine, etc.).  Combined chlorine is still a disinfectant but it is a much weaker, ineffective form of chlorine.” IPSSA Basic Training Manual, 2006 pg 172 Glossary

Combined chlorine is treated by adding more chlorine until the “break point”  is reached. “Breakpoint chlorination is the process of adding sufficient free available chlorine to completely oxidize all organic matter and ammonia or nitrogen compounds.”  IPPSA Basic Training Manual, 2006, pg 168 Glossary

Shock treatment is the practice of adding significant amounts of an oxidizing chemical (usually non-chlorine oxidizers such as sodium persulfate or potassium peroxymonosulfate) to the water to destroy ammonia and nitrogen compounds or swimmer waste.” IPPSA Basic Training Manual, 2006 pg 188 Glossary