The chlorine that you dissolve into your pool water combines with bacteria and other organics in the water on a molecular level to kill these harmful contaminants. When the chlorine “combines” with the bacteria and organics in the water, the chlorine molecules become inactive and no longer work to sanitize your pool. The combined chlorine and contaminants are burned up by your weekly shock treatment, and removed from the water by the pool filter system. The chlorine level of a swimming pool should be maintained at 1-3 ppm at all times to ensure that the pool water is clean and safe for swimmers.
There seems to be many types of chlorine on the market, and you will find a very wide range of prices. Each pool supply company works hard to make their chlorine product seem new and different, but upon close inspection you will find that the only real difference that may separate one brand of chlorine from another is the concentration of the active ingredients in the chemical. When comparing brands of chlorine you should expect a concentration of 99.5% Sodium Dichloro-S-Triazinetrione in granular chlorine, and a concentration of 99% Trichloro-S-Triazinetrione in chlorine tablets or sticks.
Chlorine is available in 3” tablets, 1” tablets, sticks and in a granular form. The type of chlorine you should use depends upon your application and your preferences or pool maintenance habits. The most common (and therefore the least expensive) form of chlorine is 3” tablets. 3” tablets are slow dissolving, which means they require less maintenance. A floating chlorine feeder or automatic feeder can be filled with a large quantity of 3” tablets, and maintain the proper chlorine level in your pool water for a week or more without any work from the pool owner.
Another form of chlorine is chlorine sticks. Chlorine sticks are larger and dissolve even slower than 3 inch chlorine tablets. 1 inch chlorine tablets are smaller and dissolve more quickly than 3” chlorine tablets. 1” chlorine tablets are better suited to smaller swimming pools and spas. The final common form of chlorine is Granular chlorine. Granular chlorine must be pre-dissolved in a bucket of water, and added to a swimming pool on an almost daily basis. This allows very precise control over the chlorine level of the swimming pool, but requires daily testing and addition of the chemical.
The chemical “Bromine” is very similar to chlorine in the way that it kills bacteria and harmful contaminants, but the two chemicals react in different ways in the swimming pool water. Bromine is most commonly used to sanitize spas/hot tubs because it is more stable than chlorine in the warmer temperatures. The advantages to using bromine are obvious, and bromine is very beneficial to many people with naturally sensitive skin. Although bromine produces less of a chemical odor than chlorine, it is harder to wash away the chemical smell from your skin after bathing in a bromine pool or spa. Bromine is available in tablet form and should be added to pool or spa water using a chemical feeder to dissolve the tablets.
The difference between the chemical chlorine and the chemical bromine is that once chlorine combines with bacteria to kill it, most of the chlorine is used up and will no longer work to sanitize your pool. This combined chlorine is burned off along with the bacteria by the weekly shock treatment, and filtered out of the pool water. Bromine combines with bacteria in pool water to neutralize it in the same way that chlorine does, however a good portion of the bromine stays active even after combining with the bacteria. The weekly shock treatment will burn off the bacteria and harmful contaminants, and leave the bromine behind in the pool water to sanitize the pool again. The result is that the volume of the chemical bromine needed to sanitize a pool is less than the volume of chlorine needed to do the same job.
The advantages to using bromine are obvious, and bromine is very beneficial to many people with naturally sensitive skin. Unfortunately bromine is chlorine based, and it is not an alternative sanitizer for people who are allergic to chlorine. The very big disadvantage to bromine is the cost of the chemical. Bromine costs a good deal more per pound than chlorine, which prevents most pool owners from using it.