Commercial Clearwater Company, Inc.
Gas Chlorine: In its elemental state, chlorine exists as a gas. This form of chlorine was popular in swimming pool use because it is very cheap, and is the purest form of chlorine with no binders or carriers, and 100% of the chlorine is available for use. Most pool are phasing out the use of chlorine gas because it is extremely dangerous and its storage and use is highly regulated by Federal, State and Local authorities. Gas is also acidic, with a pH close to muriatic acid, causing pools using gas to also use a lot of Ph reducer to counteract it.
Liquid Chlorine: is another form of chlorine in popular use because it is also relatively inexpensive. This form of chlorine is chemically identical to bleach, and provides only 10 -15 % of available chlorine in solution. Liquid Chlorine also has a high pH of about 13. Liquid Chlorine is called Sodium Hypochlorite (NaOCl) and because it is already in solution, it produces hypochlorous acid instantly when it contacts water. The liquid can be poured directly into the pool, but it is recommended to use a diaphragm or peristaltic pump. Liquid chlorine is used in larger commercial pools where it is also highly regulated in how it may be transported, stored, and used. For most residential pools its lower cost is outweighed by its difficulty of use, safety issues, and the amount of acid required to counteract its high pH.
Solid Chlorine: Chorine is most popularly used, particularly in residential pools, in tablet, granular of other solid form.
- Trichlor: (Trichloro-s-triazinetrione) is a tablet form of chlorine. It is manufactured by combining the salts of cyanuric acid and chlorine gas into a tablet or stick, and provides about 90% available chlorine. Trichlor has a low pH of about 3.0 so pool water pH may tend to drop with Trichlor's use. Trichlor dissolves slowly so it works best in floaters or in-line erosion feeders more popular in residential pools. Using tablets in the skimmer is not recommended, because of the corrosive nature of the chemical contacting metal pipes and equipment. Nor should tablets be thrown directly into the pool where they can stain and etch plaster and bleach and deteriorate vinyl.
- Dichlor: (Sodium Dichloro -s-triazinetrione.) is a granular form of chlorine. It is made in roughly the same manner as trichlor, however as a granule it dissolves faster making chlorine available at a quicker rate, but has less available chlorine by weight than Trichlor, around 62%. It also has an almost neutral pH of around 7.0. Dichlor's main drawback is it's cost per pound of available chlorine. It is perhaps the most expensive form of chlorine available.
- Lithium: Lithium Hypochlorite, like dichlor, is a granular form of chlorine which dissolves rapidly, and like dichlor is very expensive in terms of its available chlorine by weight. At only 35% available chlorine it would take almost 3 lbs of lithium to equal one lb of trichlor. It also has a high pH of 11 which requires additions of an acid to maintain balanced pool water.
- Calcium Hypochlorite ("cal hypo" ) is available in tablet or granular form. This form provides about 65% available chlorine by weight and has a high pH of around 12.0.