Since mankind decided that hot tubs would be fun we have had to face the challenge of keeping that water clear and safe. Chlorine and Bromine have been in use since almost day one. Both have their advantages. They kill everything. The down side is also that they kill everything. By that I mean that Chlorine and Bromine are both caustic chemicals. That is both how they function and what makes them less desirable. Not only do they kill germs and bacteria but they are harmful to your skin, hair, bathing suits, spa jets, pump impellers, pets and environment. With the heightened awareness of the environment and our own physical health, there has been a wide variety of alternatives to the old standards.