A-D

Acid - A sour chemical substance containing hydrogen with the ability to dissolve metals, neutralize alkaline materials and combine with bases to form salts. Acid is used to lower the pH and total alkalinity of swimming pool and spa water. Examples are muriatic acid and dry acid.

Acid Demand - The amount of acid required to bring high pH and total alkalinity down to their proper levels. Determined by the acid demand test.

Acid Demand Test - 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.

Acid Rain - Precipitation having an unusually low pH value (4.5 or lower) caused by absorption of air polluted by sulfur dioxide, carbon dioxide, and nitrous oxide.

Acrylic - A thermoplastic sheet formed into a mold to make a spa or related equipment. It is first heated and then vacuumed onto the mold.

Air Blower - A mechanical device that forces air through holes in the floor, bubbler ring, or hydrotherapy jets in a spa.

Air-Relief Valve - A brass or plastic manually operated valve located at the top of a filler tank for relieving the pressure inside the filter and for removing the air inside the filter (called "bleeding the filter"). Sometimes called a pressure-relief valve.

Algae - Microscopic plant-like organisms that contain chlorophyll. Algae are nourished by carbon dioxide (CO2) and use sunlight to carry out photosynthesis. It is introduced by rain or wind and grows in colonies producing nuisance masses. Algae are not disease-causing, but can harbor bacteria and be slippery. There are 21,000 known species of algae. The most common pool types are black, blue-green, green, and mustard (yellow). Pink or red-colored algae-like organisms exist but are bacteria and not algae. Maintaining proper sanitizer levels, shocking, and super chlorination will help prevent its occurrence.

Algaecide - Also called algicide. A natural or synthetic chemical designed to kill, destroy, or control algae.

Alkali - Also called base. A class of compounds which will react with an acid to give a salt. Alkali is the opposite of acid.

Alkalinity - Commonly called total alkalinity. A measure of the pH-buffering capacity of water. Also called the water's resistance to change in the pH. Composed of the hydroxides, carbonates, and bicarbonates in the water. One of the basic water tests necessary to determine water balance.

Alum - Any one of several aluminum compounds used in pools to form a gelatinous floc on sand filters or to coagulate and precipitate suspended particles in the water.

Ammonia - Introduced into the water by swimmers as waste (sweat or urine) or by other means. Quickly forms foul-smelling, body-irritating chloramines: a disabled, less effective form of chlorine. See chloramines or combined chlorine.

Anti-foam - A chemical added to the water to make the suds or foam go away. These products do not remove the source of the sudsing. Most often, the water must be drained and refilled to remove the soaps, oils, and other causes of foaming. Shocking and super chlorination may help prevent foaming.

Ascorbic Acid - A chemical compound used to remove iron stains from fiberglass and vinyl-liner pools.

Automatic Pool Cleaner - A pool maintenance system that will agitate or vacuum debris from the pool interior automatically.

Available Chlorine Content - A term or index used to compare the oxidizing power of chlorine-containing products to gas chlorine. It permits easy comparison of chlorine compounds.

Available Chlorine - The amount of chlorine, both free and combined in the pool water, that is available to sanitize or disinfect the water. Sometimes called residual chlorine.

B

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.

Bacteria - Single-celled microorganisms of various forms, some of which are undesirable or potentially disease-causing. Bacteria are controlled by chlorine, bromine, or other sanitizing and disinfecting agents.

Bactericide - A chemical or element that kills, destroys, or controls bacteria.

Baking Soda - Chemically called sodium bicarbonate. It is white powder used to raise the total alkalinity of pool or spa water without having much effect on pH.

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

Ball Valve - A simple non-return valve consisting of a ball resting on a cylindrical seat within a liquid passageway.

Base - Also called basic. A class of compounds which will react with an acid to give a salt. Base is the opposite of an acid. See alkali.

Bleach - This term usually refers to liquid chlorine (sodium hypochlorite). It is the same chemical used in laundry bleach but pool chlorine is 12% available chlorine while laundry bleach is about 5-6% available chlorine.

Blower - An electrical device that produces a continuous rush of air to create the optimal bubbling effect in a spa, hot tub, or whirl-pool. It is usually plumbed in with the hydrotherapy jets or to a separate bubbler ring.

Blue Fingernails - A condition caused by too much copper in the pool water. Blue fingernails are not caused by chlorine. The copper may get into the water by the bad practice of placing trichlor tabs in the skimmer. This acidic product will cause low-pH water, which will dissolve metals in the equipment. The dissolved metal (usually copper) then stains hair, fingernails, and eventually, pool walls. It can also be caused by keeping the pH too low or misusing acid.

Breakpoint Chlorination - The process of adding sufficient free available chlorine to completely oxidize all organic matter and ammonia or nitrogen compounds. All chlorine added after that point is free available chlorine.

Bromamines - By-products formed when bromine reacts with swimmer waste (sweat or urine), nitrogen, or fertilizer. Bromamines are removed by super chlorination or shock treating.

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.

Brominator - A mechanical or electrical device for dispensing bromine at a controlled rate. Most often a canister or floater filled with tablets of bromine.

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 a 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.

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

Bypass - An arrangement of pipes, gates, and valves by which the flow of water may be passed around a piece of equipment or diverted to another piece of equipment; a controlled diversion.

C

Calcium Hypochlorite - 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.

Calcium Carbonate - Crystalline compounds formed in swimming pool and spa water when the calcium, pH and total alkalinity levels are too high. Once formed, the crystals adhere to the plumbing, equipment, pool walls and bottom. These crystals are better known as scale.

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

Calcium Hardness - The calcium content of the water. Calcium hardness is sometimes confused with the terms water hardness and total hardness. Too little calcium hardness and the water is corrosive. Too much calcium hardness and the water is 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.

Cartridge - A replaceable porous element made of paper or polyester used as the filter medium in cartridge filters.

Cartridge - A pool or spa water filter that uses a replaceable porous element made of paper or polyester.

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.

Chelate (Pronounced KEY-late) - also called sequester - It is the process of preventing metals in the water from combining with other components in water to form colored precipitates that stain the pool walls and bottom or produce colored water.

Chelated Copper - Copper algaecides that contain a special ingredient to prevent the copper from staining the pool walls and bottom or producing colored water.

Chemical Feeder - Any of several types of devices that dispense chemicals into the pool or spa 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 bleach- ing 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.

Chloramines - 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.). Chloramines are still disinfectants, but they are a much weaker, ineffective form of chlorine. Chloramines are removed by super chlorination or shock treating.

Chlorinator - A mechanical or electrical device for dispensing chlorine at a controlled rate. Most often a canister or floater filled with tablets of chlorine.

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).

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

Chlorine Enhancer - A chemical compound that when used in conjunction with chlorine makes the chlorine perform better as an algaecide.

Chlorine Generator - An electrical device that generates chlorine from a salt solution in a tank or from salt added to the pool water.

Chlorine Lock - This is a term that implies that an over- abundance of cyanuric acid (stabilizer or conditioner) in the water would cause the chlorine to be all "locked up." This is not true.

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

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) or water- soluble organic polyelectrolytes.

Clarity - The degree of transparency of the water.

Coagulant - An organic polyelectrolyte used to gather (coagulate) suspended particles in the water.

Combined Chlorine - 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.

Conditioner - 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.

Coping - The cap or top lip on the pool or spa 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.

Copper - It is one of nature's elements. It is also 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, finger- nails 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.

Copper Algaecide - 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.

Corrosion - 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.

Coupling - A plumbing fitting that is used to connect two pieces of pipe.

Cover, Hard Top - A cover used on pools, spas and hot tubs that rests on the lip (coping) of the pool or spa deck - not a flotation cover. Used as a barrier to swimmers and bathers, and for maintenance and thermal protection.

Cover, Solar - A cover that, when placed on the water's surface of a pool, spa or hot tub, increases the water temperature by absorption and transmission of solar radiation; reduces evaporation and prevents wine-borne debris from entering the water.

Cover, Winter - A cover that is secured around the perimeter of a pool, spa or hot tub that provides a barrier to bathers and debris when the pool, spa or hot tub is closed for the season.

Cyanuric Acid - Also called condition 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.

D

D. E. Filter - Diatomaceous Earth Filter - A filter designed to use diatomaceous earth (D.E.) as the filter medium. The D.E. is added through the skimmer with the pump on, which takes the D.E. and deposits it on a grid. The D.E. then becomes the filter medium.

Decks - Those areas immediately adjacent to a pool, spa or hot tub that are specifically constructed or installed for use by bathers for sitting, standing or walking.

Defoamer - Also called anti-foam - A chemical added to the water to make the suds or foam go away. These products do not remove the source of the sudsing. Most often, the water must be drained and refilled to remove the soaps, oils and other causes of foaming. Shocking and super chlorination may help prevent foaming.

Diatomaceous Earth - Also called D.E. - A white powder composed of fossilized skeletons of one-celled 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.

Dichlor - The common name for sodium dichlor. A fast-dissolving chlorine compound containing chlorine and cyanuric acid (stabilizer or conditioner). It has a neutral pH and is quick-dissolving, so it can be used for regular chlorination or super chlorination.

Diffuser - A porous plate, tube or other device through which air is forced and divided into minute bubbles for diffusion in the water. A diffuser can also be an over drain on a sand filter. A diffuser is also used on a closed- face impeller on a pump to concentrate water flow to the center of the impeller.

Disinfect - To kill all pathogenic (disease-causing) organisms.

Dissolved Solids - Also called TDS or total dissolved solids - A measure of the total amount of dissolved matter in water. Examples are calcium, magnesium, carbonates, bicarbonates, sodium, chlorides and metals. High levels can cause corrosion, colored water or salty taste. Maximum level is usually 2500 ppm for pools. Maximum level for spas is 1500 ppm over starting level.

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 spa and then switch the flow back to the pool. A brand name diverter valve is called an Ortega valve, which is sometimes used to describe a diverter valve.

Diving Board - A recreational mechanism for entering a swimming pool, consisting of a semi-rigid board that derives its spring from a fulcrum mounted below the board and attached to the deck.

DPD - An indicator reagent used for the determination of free and total chlorine, bromine, ozone and other oxidizers in water. Better than using OTO for chlorine because it measures free chlorine.

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, spa or hot tub. It is not a drain, such as a drain on a kitchen sink. Main drains do not allow to drain to waste but rather connect to the pump for circulation and filtration.

Dry Acid - Chemically, sodium bisulfate. A dry white crystal that produces acid when added to water. It is used for lowering pH and total alkalinity. Safer to handle than muriatic acid.

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