A proper balance of the previously described water chemistry factors will provide water that will not damage pool components and is non-irritating to swimmers. It is then necessary to provide for disinfection of the water to prevent the spread of disease organisms from person to person and prevent unwanted growth of bacteria and algae in the pool.
Chlorine
The most commonly used disinfectant for swimming pools is chlorine. In its elemental form chlorine is a heavy greenish yellow gas which is so toxic that is has been used as a weapon in chemical warfare. Because of the extremely high potential for injury or death from improper use of chlorine gas, a number of chlorine compounds have been formulated to provide chlorine in forms that can be handled and used safely by swimming pool operators.
The following forms of chlorine are commonly used in swimming pools:
Gas Chlorine: 100% available chlorine
| Advantages: | Disadvantages: | |
| Cheapest form of chlorine | Extremely dangerous | |
| No residue from carriers | Special room needed for chlorine | |
| Feed equipment is expensive | ||
| Special training and safety equipment needed | ||
| Lowers pH, must constantly add pH increaser |
