Chemicals and Water Balance Glossary of Terms


Chemical containing hydrogen with the ability to dissolve metals, neutralize alkaline materials and combine with bases to form salts. Acid is used to lower (decrease) pH and total alkalinity of swimming pool and spa water. Examples are Hydrochloric acid and dry acid (sodium bisulphate).


A reagent test usually used in conjunction with a pH test to determine the amount of acid needed to lower pH and total alkalinity levels.


A Class of compounds which will react with an acid to give a salt. Alkali is the opposite of acid.


More commonly called total alkalinity. A measure of the alkaline content of water, generally expressed in PPM or mg/l, also the measure of the pH-buffering capacity of water. Composed of the hydroxides, carbonates and bicarbonates in the water. One of the basic water tests necessary to determine water balance.


The correct ratio of mineral content and pH level that prevents the water from being corrosive or scale forming.

Keeping the water balanced is an essential part of pool maintenance to ensure safe comfortable pool water and to maximise pool fabric and equipment life.


A substance or compound that stabilizes the pH value of a solution. It is also the water’s resistance to change in pH.


A compound of chlorine and calcium used as a disinfectant, sanitizer, bactericide, algaecide and oxidizer in swimming pool and spa water. It is available as a white granular material usually used for super chlorination or it is available as tablets used in a feeder for regular chlorination. It usually contains 65% available chlorine.


A soluble white salt used to raise the calcium or total hardness level in the pool or spa.


The calcium content of the water. Calcium hardness is sometimes confused with the terms water hardness and total hardness. If the pool water contains too little calcium hardness the water will tend to be corrosive. Too much calcium hardness and the water will tend to be scale forming. One of the basic water tests necessary to determine water balance. Minimum level is 150 ppm. Ideal range is 200 to 400 ppm.


A chemical used to make chlorine harmless. Used in test kits to counteract the bleaching effect of the chlorine or bromine in order to increase the accuracy of pool water tests. Sold as chlorine and bromine neutralizer, it is used to destroy excessive amounts of chlorine or bromine, so the high levels will not affect swimmers.CHLORINE

A term used to describe any type of chlorine compound used as a disinfectant in swimming pool and spa water or to kill, destroy or control bacteria and algae. In addition, chlorine oxidizes ammonia and nitrogen compounds (swimmer and bather waste).


The amount of chlorine necessary to oxidize all organic matter (bacteria, algae, chloamines, ammonia and nitrogen compounds) in the pool or spa water.


The amount of chlorine left in the pool or spa water after the chlorine demand has been satisfied.


Undesirable, foul-smelling, body-irritating compounds formed when insufficient levels of free available chlorine react with ammonia and other nitrogen-containing compounds (swimmer and bather waste, fertilizer, perspiration, urine, etc.). Combined chlorine is still a disinfectant, but it is a much weaker, ineffective form of chlorine.


Chemically, conditioner is cyanuric acid. It slows down the degradation of chlorine in the water by sunlight. Minimum level is 10 ppm. Too much does not slow down chlorine activity or effectiveness. Conditioner does not protect bromine from sunlight.


One of nature’s elements, it is used for various parts of equipment and plumbing in swimming pools and spas. Corrosive water caused by misuse of chemicals, improper water balance, or placing trichlor tablets in the skimmer can cause copper to be dissolved from the equipment or plumbing and deposit the precipitates on hair, fingernails or pool walls. High levels of copper also cause green water. Copper is also used as an algaecide. Maximum level is about 0.2 ppm.


A chemical compound that contains the element copper. Copper sulfate was one of the original copper algaecides. Too much copper in the water can cause green-colored stains. Newer copper algaecides contain an ingredient that prevents the copper from staining but does not affect copper’s ability to kill algae. These special copper algaecides are called chelated copper algaecides.


The etching, pitting or eating away of the pool or spa or equipment. Caused by improper water balance, misuse of acid or acidic products or from soft water.


Also called conditioner and stabilizer. Chemically, conditioner is cyanuric acid. It protects chlorine in the water from being destroyed by sunlight. Minimum level is 10 ppm. Too much does not slow down chlorine activity or effectiveness. Does not protect bromine from sunlight.