Bromine
Chlorine and bromine are both members of the same chemical family known as halogens. While not as popular as chlorine, bromine has gained wide acceptance as a sanitizer, especially in hot tubs where the hot turbulent water tends to increase the amount of wastes in the water. The heavy waste accumulates and then places a stress on chlorine resulting in odors and irritation due to the buildup of combined chlorine. Bromine does not suffer from this problem. Bromine is available in three basic forms: tablets, sticks and caplets or as a two product system. When added to water, bromine forms hypobromous acid (HOBr) similar to the hypochlorous acid formed by chlorine. However, unlike chlorine, the amount of hypobromous acid is less dependent on pH. Additionally, the combined bromine that forms when the HOBr combines with wastes in the water does not diminish bromine effectiveness like it would with chlorine. A further advantage is found in the resulting compounds, known as bromamines, which do not cause eye and skin irritation or foul odors. For this reason, it is not necessary to test for both free and combined bromine. Only a test for total bromine is needed. Bromine tablets, sticks or caplets are usually applied through some type of feeder device either in-line or, in some cases, as a floater-type feeder. The two-product system relies upon the addition of small amounts of an inert sodium bromide salt, which by itself does little. The water is then treated with an oxidizer specially suited for this purpose, or with chlorine. The oxidizer or chlorine acts to convert the sodium bromide into free bromine. When chlorine is used this way, it reacts only to make bromine and does not act as a sanitizer itself.