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 (decrease) pH and total alkalinity of swimming pool and spa water. Examples are muriatic acid (hydrochloric) and dry acid (sodium bisulfate).
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.
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.
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 it is slippery. There are 21,000 known species of algae. The most common pool types and black, blue-green, green and mustard (yellow or drawn). 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 algaecide – 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 Also more commonly called total alkalinity. A measure of the pH-buffering capacity of water. Also called the water’s resistance to change in pH. Composed of the hydroxides, carbonates and bicarbonates in the water. One of the basic water tests necessary to determine water balance.
AMMONIA Introduced into the water by swimmers as waste (perspiration 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.
AVAILABLE CHLORINE CONTENT A term used or an index used to compare the oxidizing power of chorine-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. Some- times called residual chlorine.
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 affect on pH.
BALANCED WATER The correct ratio of mineral content and pH level that prevents the water from being corrosive or scale forming.
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 12% available chlorine). It is the same chemical used in laundry bleach but pool chlorine is 12% available chlorine while laundry bleach is about 5 to 6%% available chlorine. Not recommended for vinyl spas.
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.
BREAKPOINT CHLORINATION 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 (perspiration or urine), nitrogen or fertilizer. Bromamines are active disinfectants and do not smell, although high levels are body irritants. 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 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 sodium bromide, a granular salt. Ideal for use in spas, especially for vinyl spas.
BUFFER A substance or compound that stabilizes the pH value of a solution. It is also the water’s resistance to change in pH.
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 FILTER 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 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 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.
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.
CLARIFIER Also called coagulant or flocculant – A chemical compound used to gather (coagulate or agglomerate), or to precipitate suspend- ed particles so they may be removed by vacuuming or filtration. The are two types; inorganic salts of aluminum (alum) or water soluble organic polyelectrolyte.
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.
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 wind-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.
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.
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.
DISINFECT To kill al 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.
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 the 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.
EFFLUENT The water that flows out of a pump, filter or heater, usually on its way back to the pool or spa.
ELBOW A plumbing fitting shaped at a 90 degree or a 45 degree angle usually made of metal, PVC or some other plastic.
EPA Abbreviation for the federal Environmental Protection Agency.
FIBERGLASS Fine spun 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, spas and related shapes.
FILTER A device that removes undissolved 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).
FILTER AREA The total surface area of the filter medium that is exposed to the flow of water from the pump, expressed in square feet. Examples are: a 36 sq. ft.. (also 36 ft2) D.E. filter and a 100 sq. ft.. (also 100 ft2) cartridge filter.
FILTER CARTRIDGE A replaceable porous element made of paper or polyester used as the filter medium in cartridge filters.
FILTER CYCLE The operating time between cleaning or backwashing cycles of a filter. Also the amount of time the filter has water flowing through it each day expressed in hours.
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 – abbreviated as gpm.
FOAM A froth of bubbles on the surface of the water. Usually comes from soap, oil, deodorant, hair spray, suntan oil, etc., that is shed into the water as swimmers enter.
FREE AVAILABLE CHLORINE The amount of free chlorine in the pool or spa water that is available to sanitize or disinfect the water. Sometimes called residual or available chlorine.
GPD An abbreviation for gallons per day.
GPH An abbreviation for gallons per hour.
GPM An abbreviation for gallons per minute.
GROUND-FAULT CIRCUIT INTERRUPTER Also called a GFCI – A device intended to protect people. It interrupts (de-energizes) the electrical circuit whenever it detects the presence of excess electrical current going to ground (usually 1/40th of a second and 5/1000th of an ampere).
HALOGENS 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.
HAND SKIMMER A screen attached to a frame which is then attached to a telepole used to remove large floating debris, such as leaves and bugs, from the water’s surface.
HARDNESS The amount of calcium and magnesium dissolved in the water. "Water" or "total" hardness refers to the total magnesium and calcium dissolved in the water. Calcium hardness refers to just the calcium. Measured by a test kit and expressed as ppm. The proper range is 200 to 400 ppm.
HOT TUB A spa constructed of wood with the sides and bottom formed separately and joined together by hoops, bands or rods.
HYDROCHLORIC ACID 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.
HYDROGEN 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.
HYDROGEN ION 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.
HYDROGEN PEROXIDE 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.
HYDRO JET A fitting in the pool or spa on the water return line from the equipment that blends or mixes air and water, creating a high- velocity, turbulent stream of air-enriched water.
HYPOBROMOUS ACID The most powerful disinfecting form of bromine in water. Sometimes called the killing form of bromine.
HYPOCHLOROUS ACID The most powerful disinfecting form of chlorine in water. Sometimes called the killing form of chlorine.
IMPELLER The rotating member of a pump. The part of the pump that moves the water.
INFLUENT The water entering the pump, the filter or other equipment of space. Water going into the pump is called in influent, while water leaving the pump is called the effluent.
INLET A fitting in the pool or spa on the water return line from the equipment that water returns to the pool. Usually the last thing on the return line.
IRON 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.
JACUZZI® A brand name and registered trademark for a specific line of spas and whirlpools. Also a slang term used improperly to describe a hot tub or spa.
LINER Also called vinyl line – The vinyl membrane that acts as the container to hold or contain the water.
LIQUID ACID (31.45% hydrochloric acid) – also called muriatic acid – It is used for lowering pH, total alkalinity and for various cleaning needs. It is also used for acid washing.
MAGNESIUM HARDNESS A measure of the amount of magnesium dissolved in the water. It is part of total or water hardness. It also causes scale if levels are too high.
MAIN DRAIN This term usually refers to a plumbing fit- ting installed on the suction side of the pump in pools, spas and hot tubs. Sometimes called the drain and 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 the water to drain to waste but rather connect to the pump for circulation and filtration.
MAKE-UP WATER This is sometimes called "tap" or "refill" water. It is the water used to replace water lost to evaporation, splash-out, leaks or swimmer drag-out in the pool.
MINERAL Any substance that is neither animal or vegetable. It is any class of substances occurring in nature, usually comprising of inorganic substances, such as quartz , of definite chemical composition and definite crystal structure. It sometimes includes rocks formed by these substances. Ground water dissolves these rock substances, and the dissolved minerals are present in tap water. Depending on the kinds of rocks the water comes in contact with, the minerals dissolved in the water may be just a few or they may be many. Water hardness is mostly comprised of these minerals.
MURIATIC ACID (31.45% hydrochloric acid) – Also called liquid acid – An acid used to reduce the pH and alkalinity levels in pool water. It is also used in acid washing, a process that removes stains and scale from pool plaster.
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.
NITROGEN A gas that causes algae to bloom and disables chlorine. It is brought into the water each time it rains. Maintaining proper chlorine levels will prevent nitrogen from becoming a problem. Super bromination will remove nitrogen and its related compounds.
NON-CHLORINE SHOCK A term given to a class of chemical compounds that are used to oxidize or shock the water (destroy ammonia, nitrogen and swimmer waste). They contain no chlorine or bromine and do not kill living organisms. Swimmers may re-enter the water in only 15 minutes after adding a non-chlorine shock.
NORYL The brand name for a thermoplastic resin used in the manufacturing of certain pump components and various other pool equipment fittings.
ORGANIC Refers to volatile, combustible and sometimes biodegradable chemical compounds containing carbon atoms bonded together with other elements. The principal groups of organic substances found in water are proteins, carbohydrates, fats and oils. See organic waste.
ORGANIC WASTE Also called swimmer or bather waste – All of the soap, deodorant, suntan lotion, lipstick, makeup, cologne, body oils, sweat, spit, urine, etc., brought into the water. They also form chloramines, which are foul-smelling and body irritants. Requires large amounts of bromine or non-chlorine shock to destroy.
ORP An abbreviation for oxidation reduction potential. It is a measurement of a body of water’s ability to oxidize contaminants. Measured with an electrode and an electronic meter. It is an indication of the sanitizing level or degree of safety from disease in the water. Measured in millivolts with the accepted minimum level being 650 mV (millivolt).
OXIDATION To rid the water of ammonia, nitrogen compounds and swimmer waste (organic compounds). These organic compounds disable chlorine, are body irritants and have a foul smell. Removal is accomplished by super bromination or by shock treating with a non-chlorine oxidizer.
OXIDIZER A non-chlorine shocking compound that removes or destroys built-up contaminants and chloramines in pool water without raising chlorine levels as required when "super chlorinating."
OZONATOR A gaseous molecule comprised of 3 atoms of oxygen. It is generated on site from air or oxygen and used for oxidation of water contaminants.
PATHOGENIC ORGANISM An organism that causes disease.
pH A term used to indicate the level of acidity or alkalinity of pool water. Too low of pH causes etched plaster, metal corrosion and eye irritation. Too high of pH causes scale formation, poor chlorine efficiency and eye irritation. The ideal range for pH in swimming pools is 7.4 to 7.6.
PHENOL RED A chemical reagent dye used to test for pH. It can measure pH from 6.8 to 8.4.
POTASSIUM PEROXYMONOSULFATE The active ingredient and chemical name of a non- chlorine shock treatment or non-chlorine oxidizer. Does not kill bacteria or algae but it will oxidize or destroy ammonia, nitrogen and swimmer waste. It has a low pH, and it does not increase chlorine or bromine levels the way that super chlorination does, so water may be entered in 15 minutes after addition. It will also reactivate bromine to its killing form, hypobromous acid.
ppm An abbreviation for parts per million. It is a weight-to-weight expression. It means 1 part in 1 million parts, such as 1 lb. of chlorine in 1 million lbs. of water. Many of the common pool water tests, as well as acceptable ranges, are stated as ppm. For example, free available bromine should be kept between 2.0 and 5.0 ppm; total alkalinity should be between 80 and 120 ppm; and and water hardness should be between 200 and 400 ppm.
PRECIPITATE A substance separating, in solid particles, from a liquid as a result of a chemical or physical change. It also means to form a precipitate.
psi An abbreviation for pounds per square inch.
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 spa water. Typicaly, 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 gallons per minute (gpm).
RATE OF FLOW The quantity of water flowing past a design- ated point within a specified time, such as the number of gallons flowing past a point in 1 minute – abbreviated as gpm.
REAGENTS The chemical agents, dyes, indicators or titrants used in testing various aspects of water quality.
RESIDUAL BROMINE The amount of measurable bromine remaining after treating the water with bromine. The amount of bromine left in the pool or spa water after the bromine demand has been satisfied.
RESIDUAL CHLORINE The amount of measurable chlorine remaining after treating the water with chlorine. The amount of chlorine left in the pool or spa water after the chlorine demand has been satisfied.
SODIUM SESQUICARBONATE A chemical mixture of equal parts of soda ash and sodium bicarbonate used to increase pH and total alkalinity in pool and spa water. It has a pH of 10.1.
SANITIZE To render sanitary: to kill all living things, including bacteria and algae. Similar to sterilize.
SCALE The precipitate that forms on surfaces in contact with water when the calcium hardness, pH or total alkalinity levels are too high. Results from chemically unbalanced pool and spa water. Scale may appear as grey, white or dark streaks on the plaster, fiberglass or vinyl. It may also appear as a hard crust around the tile.
SCUM The extraneous or foreign matter which rises to the surface of the water and forms a layer or a film there. It can also be a residue deposited on the tile or walls of the pool or spa. Sources of scum are soap, oil, deodorant, hair spray, suntan lotions and others.
SEDIMENT The solid material settled out from the water.
SEQUESTERING AGENT Also called chelating agent – A chemical that will combine with dissolved metals in the water to prevent the metals from coming out of solution (precipitating or causing stains). May also be a chemical that removes dissolved metals from water.
SHOCK TREAT 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 com- pounds or swimmer waste.
SILT Soil particles having diameters between 0.004 and 0.062 mm (millimeters). Sometimes they may be too small to be trapped by the circulation system. In those cases, a clarifier or an alum product may be needed.
SKIMMER A device installed through the wall of a pool or spa 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 WEIR Part of a skimmer that adjusts automatically to small changes in water level to assure a continuous flow of water to the skimmer. The weir also prevents debris from floating back into the pool when the pump shuts off.
SODA ASH (Sodium Carbonate) – A chemical used to raise total alkalinity in pool and spa water with only a slight affect on the pH.
SODIUM BICARBONATE (Baking Soda or Bicarbonate) – A chemical used to raise total alkalinity in pool and spa water with only a slight affect on the pH.
SODIUM BISULFATE (dry acid) – A chemical used to lower the pH and total alkalinity. 2 1/2 lbs. of dry acid are equal to 1 quart of muriatic acid.
SODIUM BROMIDE A salt of bromine. It is used to establish a bromide "bank" in pool and spa water prior to beginning the use of bromine tablets.
SODIUM DICHLOR A fast-dissolving, granular, stabilized organic chlorine compound providing either 56% or 63% available chlorine. Used for regular as well as super chlorination. Contains an ingredient (cyanuric acid or stabilizer) that prevents the chlorine from being destroyed by the ultraviolet (UV) rays of the sun. Recommended for use in fiberglass pools and acrylic or fiberglass spas.
SODIUM HYPOCHLORITE Liquid chlorine. Usually provides 10% to 12% available chlorine; has a pH of 13 and re- quires that small amounts of acid be added to the pool to neutralize the high pH. Good for regular chlorination and super chlorination. Not recommended for spas. Does not contain conditioner or stabilizer to protect it from sunlight, but it is protected if stabilizer or conditioner is already in the water.
SODIUM PERSULPHATE Active ingredient and chemical name of a non-chlorine shock treatment or non-chlorine oxidizer. Does not kill bacteria or algae but it will oxidize or destroy ammonia, nitrogen and swimmer waster. Does not increase chlorine or bromine levels the way that super chlorination does, so water may be entered in 15 minutes after addition. It will not reactivate bromine.
SODIUM THIOSULPHATE A chemical used to neutralize or de-chlorinate pool and spa water.
SOFT WATER Water that has a very low calcium and magnesium content (water hardness) – usually means less than 100 ppm or 6 grains. Also water that has gone through a water softener. Pools and spas should never be filled with soft water from a softener. Water with less than 100 ppm of hardness should be increased to a minimum of 150 to 200 ppm using calcium chloride.
SOLAR COVER 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 wind-borne debris from entering the water.
SODIUM CARBONATE (soda ash) – A chemical used to raise the pH and total alkalinity in pool and spa water.
SOURCE WATER Also called "tap" water – It is the water used to fill or refill the pool or spa.
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. 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 super chlorination 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 in-line erosion type) used for regular chlorination only. Not recommended for vinyl spas.
STAIN A discoloration or a colored deposit on the walls or bottom of a swimming pool or spa. Most often, stains are metals, such as iron, copper & manganese. They may appear as green, gray, brown or black. They may even discolor the water. Sometimes a sequestering agent or chelating agent will remove them. If not, usually an acid wash is necessary to remove them from the walls & bottom. The metals get in the water because the pH was too low or someone has added a low-pH chemical directly into the circulation system. The low-pH chemical dissolves a small amount of metal from the equipment. The metals begin to come out of solutions & deposit or stain the walls & bottom. Stains are sometimes confused with scale.
STAIN INHIBITOR Also called sequestering or chelating agent- A chemical that will combine with dissolved metals in the water to prevent the metals from coming out of solution (precipitating or causing stains). May also be a chemical that removes dissolved metals from water.
SUPER CHLORINATION The practice of adding an extra large dose (5 to 10 ppm) of chlorine to the water to destroy ammonia, nitrogen and swimmer waste, which can build up in the water. This level of chlorine is required to destroy all of the combined chlorine in the water, which is called breakpoint chlorination.
SUSPENDED SOLIDS Insoluble solid particles that either float on the surface of or are in suspension in the water, causing turbidity. They may be held in suspension by agitation or flow. They may be removed by filtration, but if the particles are too small, they may not be trapped by the filter. In these cases, a clarifier or alum may be needed to remove them.
TEST KIT An apparatus or device used to monitor specific chemical residuals, levels, constituents or demands in pool or spa water. Kits usually contain reagents, vials, titrants, color comparators and other materials needed to perform tests. The most common pool and spa 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.
TOTAL ALKALINITY The total amount of alkaline materials pre- sent in the water. Also called the buffering capacity of the water. It is the water’s resistance.