Chlorine is available in three basic forms: gas, liquid, and solid. Although gas chlorine is the most effective and inexpensive type of chlorine, it is also extremely toxic and can even be lethal. For the most part, gas chlorine is not allowed in residential pools - it is mainly used in commercial and public pools. Therefore, this discussion will explain chlorine in its liquid and solid forms only. These traditional forms of chlorine are unstable, that is, they dissipate quickly in sunlight, although there are some newer forms of chlorine that are stabilized.

Perhaps the greatest disadvantage of chlorine is the production of combined chlorine in pools. When free available chlorine (FAC) combines with nitrogenous organic wastes that swimmers naturally bring into the pool (perspiration oil, and so on), the result is obnoxious odors. This compound is called combined available chlorine (CAC) and can only be destroyed by high additional doses of chlorine.

It is important to understand that the chlorine you think you smell is not chlorine., When foul-smelling swimming pool odors reach your nose, the problem is that there is actually an insufficient amount of chlorine in the water - not too much. When pool water begins to burn, irritate, and smell, it's time to replace bad chlorine with lots of good chlorine.

That said, it's important to check your pool water daily for three different chlorine components. The first of the three components is free available chlorine (FAC), or simply free chlorine, the active chlorine that disinfects and oxidizes the pool, keeping it safe and comfortable. Free chlorine is "good" chlorine. But as more people enter your pool, free chlorine combines with natural body by-products to create chloramines or "bad-chlorine." This makes for the second component of chlorine, combined available chlorine (CAC.) CAC is a major pool problem and can take much of the joy out of swimming.

Ironically, in order to purge the pool of chloramines, ten times the amount of combined chlorine must be added to the pool in free chlorine. Most test kits explain ho to do this. For instance, if the FAC reading is 1.0ppm or mgl, and the total available chlorine (TAC), the third component of chlorine, reading 3.0 ppm/mgl, then 20 ppm/mgl of free chlorine must be added to rid the pool of 2.0 ppm/mgl (CAC) (TAC-FAC=CAC x 10 ppm/mgl). This required remedy is called shocking, or superchlorination, and requires that you either close your pool temporarily until the free chlorine drops to an acceptable level or use nonchlorine shocking agents.

Water Chemistry • Popular Disinfectants • Chorine • Calcium Hypochorite • Sodium Hypochlorite • Stabilized Chlorines •
Bromine • Other Disinfectants • Water Balance • pH • Total Alkalinity • Calcium Hardness • Total Dissolved Solids •
Balancing Pool Water • Water Testing • Pool Vacs & Sweepers

Pool Maintenance • Daily Chores • Weekly Chores • Solving Common Problems • Cloudy, Milky Water • Malodorous, Irritating Water
Green Water • Red or Brown Water • Blue - Green Water • Blue or Black Water • Pump Problems • Sand in Pool •
Excessive Water Loss • Excessive Foaming