Disinfectants and Santisers Glossary of Terms


The chemical elements either individually or collectively that constitute Group VIIB of the Periodic Table of Elements: fluorine, chlorine, bromine, iodine and astatine. Of these, only chlorine and bromine are used as disinfectants and sanitizers in pools and spas.


Also called muriatic acid – A very strong acid used in pools to lower the pH and total alkalinity. It can also be used for various cleaning needs. Used in “acid washing” a pool. Use extreme care in handling.


The lightest chemical element. A component of water, and a frequent product of many chemical reactions. pH is a measure of hydrogen in its ionic form in water.


The positively charged nucleus of hydrogen atom. The relative degree of acid or base of a solution (called pH) is a measure of hydrogen ions.


An unstable, colorless, heavy liquid used as a bleach in industry and as an antiseptic in households. It is used as an oxidizing agent in pools and spas. May also be used to de-chlorinate pool or spa water.


The name given to a family of chlorine containing compounds, including calcium hypochlorite, sodium hypochlorite and lithium hypochlorite, that are used as disinfectants and sanitizers in pool and spa water.


The most powerful disinfecting form of chlorine in water. Sometimes called the killing form of chlorine.


Iron in water causes the water to be brown- or green-colored. Can be controlled by the addition of a sequestering agent or a chelating agent. Water can be tested with an iron test kit.


Also called stabilized chlorine – A family of chlorine pool sanitizers that contain conditioner (cyanuric acid or isocyanuric acid) to protect the chlorine from the degrading UV rays in sunlight. The most common types are sodium dichlor and trichlor. The granular form is dichlor, which is fast- dissolving and can be used for regular chlorination or superchlorination by broadcasting into the pool or spa. Tablet or stick form is trichlor (which is usually used in a chlorine feeder – either the floating type or the in-line erosion type) used for regular chlorination only.


A sodium hypochlorite solution. Usually provides 10 to 12% available chlorine; has a pH of 13 and requires that small amounts of acid be added to the pool to neutralize the high pH. Good for regular chlorination and superchlorination.


A dry, granular chlorinating compound with an available chlorine content of 35%. It is fast-dissolving and can be used to superchlorinate vinyl-liner pools, painted pools or fiberglass pools as well as spas and hot tubs.