Bromine
Definition
An alternative disinfectant to chlorine, occasionally used at indoor recirculated splash pads because it is more stable at warm water temperatures and produces less harsh odor.
Bromine is far less common than chlorine at U.S. splash pads but appears at some indoor installations and resort water-play areas. It tolerates warmer water and higher pH better than chlorine, which suits indoor pads kept at 84–88°F.
Drawbacks include higher cost (3–5× chlorine), no UV stabilizer equivalent to cyanuric acid, and lower efficacy against cryptosporidium. Most outdoor U.S. splash pads stick with chlorine plus UV for that reason.