Swimming Pool Terminology

As we count down to the first day of spring, the team here thought a list of swimming pool terminology might prove useful. While it may not be all encompassing, our list provides a wealth of information on most words encountered during the Canadian pool operating season. AIR-RELIEF VALVE: A manually-operated brass or plastic valve located at the top of a filter tank for relieving the pressure inside the filter and removing the air inside the filter (bleeding the filter). Also known as a pressure-relief valve. ALGAE: Microscopic plant-like organisms that contain chlorophyll. Algae is nourished by carbon dioxide (CO2) and use sunlight to carry out photosynthesis. It can be introduced by rain or wind and grows in colonies, producing nuisance masses. Algae can harbor bacteria and can be slippery. There are thousands of known species of algae. The most common types of algae found in pools are black, blue-green, green and mustard (yellow or drawn). ALGAECIDES: Chemical compounds designed to kill, prevent and control algae. AUTOMATIC POOL CLEANER: A pool maintenance system that will agitate and/or vacuum debris from the pool interior automatically. BACKFLOW: The backing up of water through a pipe in the direction opposite to normal flow. BACKWASH: The process of thoroughly cleaning the filter by reversing the flow of water through it with the dirt and rinse water going to waste. BALANCERS: Chemical compound designed to prevent corrosion and staining by balancing the pH, total alkalinity and calcium hardness in pool water. BLUE FINGERNAILS: A condition caused by too much free copper in the pool water. Can result from cheaper copper-based algaecides, overuse of these algaecides or corrosive water. See also Green Hair. BROMIDE: A common term for a bromide salt used to supply bromide ions to the water so they may be oxidized or changed into hypobromous acid, the killing form of bromine. Used as a disinfectant. BROMINE: A common name for a chemical compound containing bromine that is used as a disinfectant to destroy bacteria and algae in swimming pools and spas. Available as a tablet or as sodium bromide, a granular salt. BTU: Abbreviation for British Thermal Unit. The amount of heat necessary to raise 1 lb. of water 1 degree Fahrenheit. CENTRIFUGAL PUMP: A pump consisting of an impeller fixed on a rotating shaft and enclosed in a casing or volute and having an inlet and a discharge connection. The rotating impeller creates pressure in the water by the velocity derived from the centrifugal force. CHECK VALVE: A mechanical device in a pipe that permits the flow of water or air in one direction only. CHEMICAL FEEDER: A device that dispenses chemicals into pool or hot tub water at a predetermined rate. Some dispense chlorine or bromine while others dispense pH-adjusting chemicals. CHLORINE NEUTRALIZER: 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 hot tub water or to kill, destroy or control bacteria and algae. In addition, chlorine oxidizes ammonia and nitrogen compounds cause by swimmers. COPING: The cap or top lip on the pool or hot tub wall that provides a finished edge around the pool or spa. It can be formed, cast in place or precast, or prefabricated of extruded aluminum or rigid vinyl. It may also be part of the system that secures a vinyl liner to the top of the pool wall. CORROSION: The etching, pitting or eating away of the pool or hot tub or equipment. Can be caused by improper water balance, misuse of acid or acidic products or from soft water. COVER, hard-top: A cover used on pools that rests on the edge of the pool deck and does not come into contact with the water. COVER, solar: A floating cover that increases the water temperature by absorption and transmission of solar radiation and reduces evaporation and pollution from the environment. Sun Covers Canada offers various models to suit any pool. COVER, winter: A cover that is secured around the edges of a pool when the pool is closed for the season. DIATOMACEOUS EARTH: Also called D.E. A white powder composed of fossilized skeletons of unicellular organisms called diatoms. The skeletons are porous and have microscopic spaces. The powder is added through the skimmer with the pump on and deposits itself on a grid. The powder then becomes the filter medium. DIVERTER VALVE: A plumbing fitting used to change the direction or redirect the flow of water. Some diverter valves are used on pool/spa combinations to allow the use of the hot tub and then switch the flow back to the pool. DRAIN: This term usually refers to a plumbing fitting installed on the suction side of the pump in pools, spas and hot tubs. Sometimes called the main drain, it is located in the deepest part of the pool, hot tub or hot tub. It does not function like a drain on a kitchen sink. Pool main drains do not allow the water to drain to waste but rather connect to the pump for circulation and filtration. EFFICACY: The power to produce an effect. Chlorine's efficacy is affected by many factors, including the sun, temperature, water balance and the water's chlorine demand. ENZYMES: Used in commercial swimming pool formulations to break down and destroy oils in the swimming pool. FIBERGLASS: Finespun filaments of glass which are available in a rope or mat form. When used in a process with polyester resins, catalysts and hardeners, can be formed or molded into pools and spas. FILTER: A device that removes dissolved or suspended particles from water by recirculating the water through a porous substance (a filter medium or element). The three types of filters used in pools and spas are sand, cartridge and D.E. (diatomaceous earth). FILTRATION RATE: The rate at which the water is traveling through the filter, expressed in U.S. gallons per minute (gpm) per square foot of filter area. FLOW RATE: The quantity of water flowing past a designated point within a specified time, such as the number of gallons flowing past a point in 1 minute — also known as gallons per minute or gpm. FREE AVAILABLE CHLORINE: The amount of free chlorine in the pool water that is available to oxidize, sanitize or disinfect the water. The level can be measured using a DPD1 test kit. It is also called residual chlorine or available chlorine. GPM: Abbreviation for “gallons per minute.” GREEN HAIR: A condition caused by too much copper in the pool water or very high levels of chlorine. GUNITE: A mixture of cement and sand sprayed onto contoured and supported surfaces to build a pool. Gunite is mixed and pumped to the site dry, and water is added at the point of application. Plaster is usually applied over the gunite. GUTTER: An overflow trough at the edge of the pool through which floating debris, oil and other "lighter-than-water" things flow. Pools with gutters usually do not have skimmers. HAND SKIMMER: A screen attached to a frame which is then attached to a telescopic pole used to remove large floating debris, such as leaves and bugs, from the water's surface. HARD WATER: Water that is high in calcium, magnesium or other salts, which makes it difficult for soap to lather. Hard water also has a tendency to form scale. HEAT EXCHANGER: A device located inside the heater providing for the transfer of heat from the heat source to the water. This is usually a series of metallic tubes with fins located just above the flames. HEATER: A fossil-fueled, electric or solar device used to heat the water of a pool, hot tub or hot tub. IRON: Iron is a natural element that can cause the water to become clear brown or green in color It can also result in staining of the pool surfaces. Iron can be controlled by the addition of a suitable sequestering or chelating agent. LINER: Also called a vinyl liner. The vinyl membrane that acts as the container to hold or contain the water in some types of pools. MAIN DRAIN: A plumbing fitting installed on the suction side of the pump in pools, spas and hot tubs. Sometimes simply referred to as the drain, it is located in the deepest part of the pool, hot tub or hot tub. It does not function like the drain on a kitchen sink. Pool main drains do not allow the water to drain to waste but rather connect to the pump for circulation and filtration. NEUTRALIZER: A chemical used to make chlorine or bromine 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. NON-CHLORINE SHOCK: A granular form of potassium peroxymonosulfate (potassium monopersulfate, potassium permonosulfate), used to oxidize materials such as microorganisms, contaminants (ammonia, nitrogen, swimmer waste) or chloramines. ORGANIC WASTE: Also called swimmer or bather waste. Refers to the soap, deodorant, suntan lotion, body oils, sweat, spit, urine, etcetera introduced into the water by swimmers, as well as the leaves, dust and insects that end up in the pool. The organic waste may form undesirable chloramines, which require large amounts of chlorine or non-chlorine shock to be destroyed. OXIDIZER: A non-chlorine shocking compound that removes or destroys built-up contaminants and chloramines in pool water without raising chlorine levels. PUMP: A mechanical device, usually powered by an electric motor, which causes hydraulic flow and pressure for the purpose of filtration, heating and circulation of pool and hot tub water. Typically, a centrifugal pump is used for pools, spas and hot tubs. PUMP CAPACITY: The volume of liquid a pump is capable of moving during a specified period of time. This is usually listed in gallons per minute or gpm. PUMP CURVE: Also called a pump performance curve. A graph that represents a pump's water flow capacity at any given resistance. pH: A term used to indicate the level of acidity or alkalinity of water. A pH of 7.0 is neutral; below 7 is acidic; above 7 is alkaline or basic. pH is a logarithmic expression of the measure of positive Hydrogen ions in water. The ideal range for pH in swimming pools is 7.0 to 7.6. The pH of our tears is 7.2 to 7.4 . SANITIZE: To kill all microorganisms, including bacteria and algae, and to remove unwanted contaminants. SCUM: The foreign matter which floats to the surface of the water and forms a layer or a film. It can also refer to a residue deposited on the tiles or walls of the pool. SEDIMENT: The solid material that precipitates out of the water and settles to the floor of the pool. SEQUESTERING AGENT: Also called Chelating Agent. A chemical or compound that combines with dissolved metals or minerals in the water to prevent them from coming out of solution, thus coloring the water or causing stains. SEQUESTRANT: A chemical which holds metals in solution and helps prevent scaling. See Sequestering Agent. SHOCK TREATMENT: The practice of adding significant amounts of an oxidizing chemical -- (usually non-chlorine oxidizers, such as sodium persulfate or potassium peroxymonosulfate) -- to the water to destroy ammonia and nitrogen compounds caused by swimmers, the environment and/or weather. SKIMMER: A device installed through the wall of a pool or hot tub that is connected to the suction line of the pump that draws water and floating debris in the water flow from the surface without causing much flow restriction. SKIMMER BASKET: A removable, slotted basket or strainer placed in the skimmer on the suction side of the pump, which is designed to trap floating debris in the water flow from the surface without causing flow restriction. SODIUM BICARBONATE: Also called Baking Soda or Bicarb. A base that is used to raise Total Alkalinity in pool water with only a slight effect on the pH. Sodium bicarbonate can only raise the pH of the water to 8.5, regardless of the amount used. Care should be taken, however, to avoid adding large quantities at one time. SOFT WATER: Water that has a low calcium and/or magnesium content. Soft water can result in the etching of the pool's surfaces, and should be increased with calcium chloride. SOLAR COVER: A floating pool cover that increases the water temperature by absorption and transmission of solar radiation. It also reduces evaporation and pollution from the environment. Sun Covers Canada sells various models to suit all pools. SOLAR HEATING SYSTEM: A system that consists of panels through which the pool water passes to increase its temperature by using the sun's heat. STAIN INHIBITOR: Also called a Sequestering or Chelating Agent. A chemical that will combine with dissolved metals in the water to prevent the metals from coming out of solution and so avoiding discoloration of the water or stains. SUPERCHLORINATION: Adding 7 - 10 times the normal dose of chlorine to the water to destroy ammonia, nitrogen, chloramines and other contaminants. SUSPENDED SOLIDS: Insoluble solid particles that either float on the surface or are in suspension in the water causing cloudiness. They may be removed by filtration, but if the particles are too small a flocculant or coagulant is necessary to enable the filter to trap them. TEST KIT: An apparatus or device used to monitor specific chemical residuals, levels, constituents or demands in pool or hot tub water. The most common pool and hot tub water tests are: pH, total alkalinity, free available chlorine, water hardness, cyanuric acid, iron and copper. TEST STRIPS: Small plastic strips with pads attached that have been impregnated with reagents that can be used to test pool water for residuals, levels, constituents or demands. The strips are usually dipped in the water, and the resulting colors of the pads are compared to a standard set of colors to determine concentration. TRICHLOR: A slow-dissolving, tablet or granular stabilized organic chlorine compound which provides 90% available chlorine and has a pH of 2.9. It must be dispensed using a floating feeder or an in-line chlorinator. Trichlor contains cyanuric acid that prevents the chlorine from being destroyed by the ultraviolet rays of the sun. When using trichlor, the cyanuric acid level needs to be checked regularly to avoid chlorine lock. TURBIDITY: The cloudy condition of the water due to the presence of extremely fine particles in suspension that cannot be trapped by the filter because they are too small. Adding a clarifier, such as an organic polymer or alum, will coagulate the particles and make the filter more efficient. TURNOVER: Also called Turnover Rate. The period of time, in hours, required by the pump to circulate the volume of water in the pool. Pool capacity in kiloliters divided by pump flow rate in kiloliters per hour (m3/h) will give the turnover rate in hours. ULTRAVIOLET LIGHT TREATMENT: Using UV wavelength radiation to destroy contaminants in water. UV light is also used to create ozone molecules for the same purpose. VACUUM: Devices that use suction to collect dirt from the bottom and sides of a pool or spa. Most common is a vacuum head with wheels that attaches to a telepole and is connected to the suction line, usually via the opening in the skimmer. Pool vacuums must be operated by a person, and debris is collected in the filter. VINYL LINER: The vinyl membrane that acts as the container to hold or contain pool water. Also called a liner. WATER CLARIFIER: Also called coagulant or flocculant . A chemical compound used to gather (coagulate or agglomerate) or to precipitate suspended particles so they may be removed by vacuuming or filtration. There are two types; inorganic salts of aluminum (alum) and other metals or water-soluble organic polyelectrolytes. WEIR: Also called a Skimmer Weir. The small floating door on the side of the skimmer over which water flows on its way to the skimmer. The weir prevents debris from floating back into the pool when the pump is off.