A chemical element, bromine is an alternative to chlorine for sanitizing pool water. In fact, it is often a good choice for indoor pools. In higher temperatures, bromine is more stable than chlorine, however it is unstable in sunlight.

Bromine is particularly effective for hot tubs and spas, thanks to its high performance in hot water.

Once dissolved in water, bromine does not have a strong smell, but it can be difficult to wash the chemical scent from the skin. It is highly corrosive to metal and dissolves more slowly than chlorine. While less of an irritant than chlorine, bromine is chlorine based, so it is not an alternative for chlorine-allergic swimmers.

Like chlorine, bromine attaches itself to bacteria to neutralize the microorganisms. Chlorine becomes largely inactive at this point, while much of the bromine remains effective. The element is left behind after shock treatments, continuing to sanitize the water. As a result, less bromine is required than chlorine. On the other hand, it is also more expensive.

Bromine comes in a tablet or granulated form and is added to the pool using a chemical feeder. Bromine levels should be kept at between 2.5 and 4 parts per million (ppm). Hot weather and high humidity can cause a drop in bromine levels.