Halogens
Halogens contain chlorine, bromine, or iodine and belong to a class known as halide compounds. The only halogens used in pools and hot tubs are chlorine and bromine.
Chlorine
Chlorine is used to kill bacteria in pools. If you are using water in a fish tank or pond, the chlorine content must be removed, or it will kill the fish.
Bromine
Bromine, though similar in content to chlorine, is becoming more and more popular. This is because bromine has a much softer scent than chlorine. Bromine is available in solid forms which can be dispensed through bromine feeders. Bromine should measure about 1 to 3 parts per million in your pool water.
