Which chlorine compound is commonly used for breakpoint chlorination?

Breakpoint chlorination is a process used to effectively eliminate chloramines and other forms of combined chlorine in water, particularly in swimming pools. The use of various chlorine compounds can facilitate this process because they all release chlorine into the water, albeit through different chemical forms.

Sodium hypochlorite, a liquid chlorine solution, is often used because it can quickly introduce chlorine into the water, raising the free chlorine levels to a point that effectively breaks the bond of chloramines. Calcium hypochlorite, a solid form of chlorine, is also commonly utilized as it dissolves in water to release chlorine, which similarly can reach breakpoint levels. Chlorine gas, while less commonly used in pools today due to safety concerns, is another effective means of achieving breakpoint chlorination since it also increases free chlorine levels in water.

Given that all of these chlorine compounds can be used to reach the breakpoint chlorination phase, the answer encompassing all of them accurately reflects the diversity of options available for pool operators to manage water quality effectively. By utilizing any of these forms, operators can ensure that chloramine levels are adequately reduced, enhancing the safety and clarity of the pool water for swimmers.