Bromine, which is commonly available in tablets the same way chlorine is, has some advantages over chlorine. While chlorine combines with contaminants to produce combined available chlorine, which is foul smelling and irritating to eyes and skin, bromine produces bromamines, which are odorless and non-irritating.

With bromine, you do not need to apply periodic shock treatments as you do with chlorine. And bromine works quickly, so swimmers can jump in the pool soon after treatment.

However, there are some drawbacks. Bromine breaks down in sunlight, so pure bromine is not very effective for outdoor pools that are shaded. For that reason, many bromine tablets contain a significant amount of chlorine to help stabilize them. And bromine is more expensive than chlorine.

For these reasons, bromine is more commonly used for indoor pools and spas than for outdoor pools.