Glossary of Pool Terms

ALGAE - Unsightly, slippery growths that color water and use up chlorine. These are actually plants that grow in water. The most common types found in pools are green, black, and mustard. Proper use of sanitizers, algaecides, and maintaining proper water balance help prevent algae from growing in your pool.

ALGAECIDE - Chemicals designed to be used in your pool to prevent, control, and kill algae.

ALKALINITY - Total alkalinity measures the pool's ability to buffer pH changes.

BACKWASH - The method regularly used to clean sand and D.E. filters by pumping water backwards through the filter media and out through a discharge or backwash fitting.

BALANCED WATER - Water is considered balanced when the pH, total alkalinity, calcium hardness, metal content, sanitizer, stabilizer (if needed), and total dissolved solids are in the proper ranges for your pool type and sanitizer type.

CALCIUM HYPOCHLORITE - One form of chlorine used to sanitize pools and spas. Usually comes in powder form and must be dissolved in water before being added to the pool or spa. This form of chlorine usually contains 65% available chlorine.

CALCIUM HARDNESS - Measure of the calcium content of the water. If it is too high, the water is corrosive. If it is too low, it will cause scale build up.

CHLORAMINES - Chlorine that has been bound up by swimmer waste. This form of chlorine will not kill algae or bacteria. The level of combined chlorine in your pool added to the free chlorine residual gives you the total chlorine reading.

CHLORINE - A sanitizer and disinfectant added to pools and spas to prevent and kill bacteria and algae. Chlorine comes in
numerous chemical forms and methods of application.

D.E. POWER - Diatomaceous earth. A white powder that is used as the filter media in D.E. filters.

FREE CHLORINE RESIDUAL - The active chlorine level in the pool water after the chlorine demand is satisfied.

IONIZER - Introduces copper ions into the water to aid in killing algae and bacteria. A chlorine residual must still be maintained and shock treatments are still required.

LIQUID CHLORINE - A sodium hypochlorite solution that only contains about 10 to 12% available chlorine and an extremely high pH, resulting in the need to add pH decreaser to your pool or spa to counteract the effects on the pH.

LITHIUM HYPOCHLORITE - A fast dissolving, granular form of chlorine that has approximately 35% available chlorine.

NON-CHLORINE SHOCK - A group of chemicals that are used to remove ammonia compounds, nitrogen compounds, and waste from swimmers. These compounds do not contain chlorine and do not kill algae or bacteria.

OZONATOR - Introduces ozone into the water. Ozone is a strong oxidizer that helps control algae and bacteria. A chlorine residual must still be maintained and shock treatments are still required, but they can help reduce the amount of chlorine you must add to your pool or spa to maintain the required residual.

pH DECREASER - An acid. Lowers the pH and alkalinity of water.

pH INCREASER - Raises pH in pool water. Add directly to pool with pump in operation. Allow pool to recirculate 2-3 hours, retest pH and repeat treatment as necessary.

pH SCALE - A system for measuring the acidity or alkalinity of water. Readings above 7 are alkaline; readings below 7 are acidic.

PPM - Parts per million, a standard measure of chemical or mineral concentration in swimming pool water.

SAND FILTER - Sand that has been cleaned and filtered for size to be used in sand filters.

SHOCK TREATMENT - Super chlorination; by adding 5-10 times normal chlorine dose. Done periodically to remove accumulated organic contaminants brought into the pool by wind, rain, bathers, etc.

SKIMMER BASKET - A container, usually plastic with a handle, located inside the skimmer that is designed to catch such things as rocks, leaves, hair, etc. to help protect the plumbing pipe and pump from clogging.

STABILIZER - A granular sun screening chemical that reduces chlorine costs. Also known as conditioner and cyanuric acid.

STRAINER BASKET - Similar to the skimmer basket, except it is located in the suction side housing of the pump.

SWIMMER WASTE - Includes such items as suntan oils, makeup, body oils, sweat, spit, urine, etc. These bind chlorine into chloramines if your chlorine level is not high enough. It requires a large quantity of chlorine or non-chlorine shock to get rid of them.

TOTAL CHLORINE LEVEL - The combination of the free chorine residual and the level of combined chlorine in your pool or spa. This number alone is not a true measure of how sanitized you pool or spa is. Remember only the free chlorine residual is what is active and working to kill algae and bacteria.

WATER CLARIFER - Collects small unfilterable particles into larger filterable masses. Does not affect pH.