The different options for hot tub chlorine are sodium dichlor, sodium trichlor, and liquid chlorine. These chemical solutions are available in granular, tablet, and liquid form, and should be added regularly to the spa water to prevent the growth of bacteria. Salt water chlorination is also possible for use with specially designed salt water hot tubs, which must be equipped with a conversion generator.
Chlorine is a chemical sanitizer that kills the types of bacteria that tend to grow in warm water. Bromine and biguanide are the other two most commonly used chemicals in the treatment of spas and hot tubs. Chlorine may also be used as a form of bi-weekly shock treatment in the water, which acts as a starving agent to prevent bacteria from feeding on organic matter in the tub. Chlorine shock treatments are not compatible with all other types of hot tub chemical products, so consumers should carefully read the warning labels on any chlorine agents purchased for use in their spa systems to ensure that all solutions used work well together.
Hot tub chlorine may be added in granular form as a safe and effective means of cleansing the water and maintaining a proper pH balance. Hot tub water should typically remain between a pH of 7.2 and 7.8. Lower or higher values can lead to the growth of scales along the surfaces of the heating equipment and interior shell, or can eat into the electrical equipment and permanently damage the tub. Granular hot tub chlorine is available as sodium dichlor, which has a neutral pH, or sodium trichlor, which has a low pH and can potentially damage the tub. Adding chlorine in this manner must be done by small spoonfuls at a time until a chlorine strip test placed in the water measures the chemicals at appropriate levels for sanitizing.
Tablet and liquid forms of hot tub chlorine are not pH neutral and can negatively affect the water content of the tub. Chlorine tablets are comprised of sodium trichlor and can, over time, significantly lower the water's pH and cause it to become acidic. Liquid chlorine tends to possess a pH around 13, greatly raising the overall pH of the tub. When spa water becomes alkaline and possesses these high pH levels, it causes the formation of calcium deposits and scales within the tub.
Salt chlorination is a type of sanitizer that may be used with salt water spas. This type of hot tub chlorine uses a low charge electrical current that is pumped through a generator to convert the salt base in the water into chlorine. This can greatly reduce the amount of cleaning the tub requires over time, and often cuts down on the amount of chemicals that must be put into the water.