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).
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.
ALGAE
Microscopic plant-like organisms. Algae are nourished by carbon dioxide (CO2) and Phosphates and use sunlight to carry out photosynthesis. Algae are introduced by rain or wind and grow in colonies producing nuisance masses. Algae are not disease-causing, but can harbour bacteria. The most common pool types are black, blue-green, green and mustard (yellow).Maintaining proper sanitizer levels, shocking and super chlorination will help prevent its occurrence. A good quality algaecide should be used to prevent algae growth. A key source of food for Algae is Phosphates so reducing Phosphates in swimming pool water will also help prevent Algae growth.
ALGAECIDE
A natural or synthetic chemical designed to kill, destroy or control algae. Can be copper based or copper free.
ALKALI
A Class of compounds which will react with an acid to give a salt. Alkali is the opposite of acid.
ALKALINITY
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.
ALUM
Any one of several aluminium 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, usually through perspiration or urine but can also be by other means. Quickly forms foul-smelling chloramines – a disabled, less effective form of chlorine. See chloramines or combined chlorine.
Shock dosing and super chlorination will help prevent Chloramines forming.
AUTOMATIC POOL CLEANER
A pool maintenance system that will vacuum or displace debris from the pool interior automatically.
BACKWASH
The process of thoroughly cleaning the filter by reversing the flow of water through the filter media and sending the dirt and rinse water 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.
BALANCED WATER
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.
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 irritating to the body. Bromamines are removed by super chlorination or shock treating.
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 mostly as a tablet or less often as a granule.
BTU
Abbreviation for British Thermal Unit. The amount of heat necessary to raise 1 lb. of water by 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.
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 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. 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.
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 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
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, chloamines, ammonia and nitrogen compounds) in the pool or spa water.
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 (stablizer 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. The 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.
COPPER
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.
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.
CYANURIC ACID
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.
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.
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 superchlorination.
DISINFECT
To kill 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, coloured 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 bisulphate. 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.
ELECTROLYSIS
An electrochemical reaction causing a black stain normally found around metal fixtures or on the pool finish. It is caused by two dissimilar metals being plumbed together or from an improper electrical grounding of pool equipment or lights. Electrolysis also means the decomposition of water and other inorganic compounds in aqueous solution by means of electricity. Chlorine generators use this principle to produce chlorine from salt in the water.
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 moulded into pools, spas and related shapes.
FILTER
A device that removes 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. D.E. filter and a 100 sq.ft. 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.
FILTER MEDIUM
The material used in the filter to trap suspended dirt particles as the water is flowing through it. The polyester or paper used in making a cartridge filter element. The sand used in a sand filter. The D.E. (diatomaceous earth) used in a D.E. filter.
FILTER, SAND
A type of filter media composed of hard, sharp silica, quartz or similar particles with proper grading for size and uniformity. The most common grade used is No. 20 in sand filters.
FILTRATION RATE
The rate at which the water is travelling through the filter, expressed in U.S. gallons per minute (gpm) per square foot of filter area.
FLOC
(See flocculation) – The clump or tuft formed when suspended particles combine with a flocculating agent.
FLOCCULATION
The combination, agglomeration, aggregation or coagulation of suspended particles in such a way that they form small clumps or tufts (called floc).
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.
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.
GPH
An abbreviation for gallons per hour.
GPM
An abbreviation for gallons per minute.
GREEN HAIR
A condition caused by too much copper in the pool water. Green hair is 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 in turn 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.
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.
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.
HEAT EXCHANGER
A device located inside the heater providing for the transfer of heat from the heat source to the water.
HEATER
A fossil-fueled, electric or solar device used to heat the water of a pool, spa or hot tub.
HORSEPOWER
The work done per unit of time. 1 horsepower equals 33,000 foot-pounds of work per minute or approximately 746 watts. Motors for pumps are rated in horsepower.
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.
HYPOCHLORITE
The name given to a family of chlorine containing compounds, including calcium hypochlorite, sodium hypochlorite and lithium hypochlorite, that are used as disinfectants and sanitizers in pool and spa water.
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.
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.
IONIZER
A water-sanitation device that uses electricity to generate metal ions, which are dispersed in the water. It works by passing a low-voltage DC current through a set of metallic (usually copper and silver) electrodes placed in line with the circulation equipment. The copper is an algaecide, while the silver is a bactericide. Does not remove swimmer waste.
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.
ISOCYANURATES
Also called 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. The 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 superchlorination 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 the in-line erosion type) used for regular chlorination only.
LIQUID CHLORINE
A sodium hypochlorite solution. Usually provides 10 to 12% available chlorine; has a pH of 13 and requires that small amounts of acid be added to the pool to neutralize the high pH. Good for regular chlorination and superchlorination.
LITHIUM HYPOCHLORITE
A dry, granular chlorinating compound with an available chlorine content of 35%. It is fast-dissolving and can be used to superchlorinate vinyl-liner pools, painted pools or fiberglass pools as well as spas and hot tubs.
MAIN 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 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.
MANIFOLD
The branch pipe arrangement that connects several input pipes into one chamber or one chamber into several output pipes. A filter manifold connects several input pipes from the filter septa back into one common pipe.
MGL
See also PPM
MGL is an abbreviation for Milligrams per Litre. Milligrams per litre and Parts per million are numerically the same for water and therefore can be used and interchanged with pool water chemistry. Both MGL and PPM are used to measure the amount of a substance that is present in a liquid. In the case of swimming pools it refers to the chemical amount within the pool water.
MICRON
A unit of length equal to 1 millionth of a meter – it is .000394 of an inch. Microns are used to describe the pore size of filter media. Sand filters have openings of 25 to 30 microns; cartridge filters have openings of 8 to 10 microns; and D.E. (diatomaceous earth) filters have openings of 1 to 5 microns. Humans, without magnification, can see objects 35 microns or larger. A granule of table salt is between 90 to 110 microns.
MINERAL
Any substance that is neither animal nor vegetable. It is any class of substances occurring in nature, usually comprising of inorganic substances, such as quartz or feldspar, 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 handness is mostly comprised of these minerals.
MULTIPORT VALVE
Also called a rotary-type backwash valve – This valve replaces as many as 6 regular gate valves. Water from the pump can be diverted for various functions by merely turning the valve handle. The water may be sent to waste, used for backwashing, bypassing the filter for maximum circulation, for normal filtration, filtering to waste (rinse), or the valve may be closed to not pass water. The pump must be off before changing a valve setting.
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 chlorination 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.
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, 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 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 chlorination 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 “superchlorinating.”
OZONE
A gaseous molecule comprised of 3 atoms of oxygen. It is generated by the exposure of air or oxygen to either ultraviolet rays or electricity and is used for oxidization of water contaminants.
PATHOGENIC ORGANISM
An organism that causes disease.
PHENOL RED
A chemical reagent dye used to test for pH. It can measure pH from 6.8 to 8.4.
POTASSIUM MONOLSULFATE
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 superchlorination does, so water may be entered in 15 minutes after addition. It will also reactivate bromine to its killing form, hypobromous acid.
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.
PRESSURE GAUGE
A gauge with an analog dial indicating the pounds per square inch (psi) of pressure that has built up within a closed container, such as a filter.
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. 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 gallons per minute (gpm).
PUMP CURVE
Also called a pump performance curve – A graph that represents a pump’s water flow capacity at any given resistance.
PUMP STRAINER BASKET
Pump Strainer Basket – A device placed on the suction side of the pump, which contains a removable strainer basket designed to trap debris in the water flow without causing much flow restriction. Sometimes called a “hair-and-lint trap.”
QUATERNARY AMMONIUM COMPOUNDS
The chemical compounds of ammonia used as algaecides.
RATE OF FLOW
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.
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.
SAND
This usually refers to the filter medium used by a sand filter. The grade most often specified by filter manufacturers is grade No. 20 with a particle size of 45 to 55 mm (millimeters).
SAND FILTER
A filter using sand or sand and gravel as the filter medium.
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 compounds or swimmer waste.
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 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 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 small floating “door” on the side of the skimmer that faces the water over which water flows on its way 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 pH in pool and spa water.
SODIUM BICARBONATE
A chemical used to raise total alkalinity in pool and spa water with only a slight affect on the pH.
SODIUM BISULFATE
A chemical used to lower the pH and total alkalinity. (dry acid)
SODIUM CARBONATE
A chemical used to raise the pH in pool and spa water. (soda ash)
SODIUM DI-CHLOR
A fast-dissolving, granular, stabilized organic chlorine compound providing either 56% or 63% available chlorine. Used for regular as well as superchlorination. 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 vinyl-liner, painted or fiberglass pools and acrylic or fiberglass spas.
SODIUM HYPOCHLORITE
Liquid chlorine. Usually provides 10% to 12% available chlorine; has a pH of 13 and requires that small amounts of acid be added to the pool to neutralize the high pH. Good for regular chlorination and superchlorination. 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 PERSULFATE
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 superchlorination does, so water may be entered in 15 minutes after addition. It will not reactivate bromine.
SODIUM THIOSULFATE
A chemical used to neutralize or de-chlorinate pool and spa water.
SODIUM TRICHLOR
(Sodium Trichlorotriazinetrione) – Potent – 90%+ available chlorine – (stabilized), found in tablet form, and dispensed in feeders, both floating and automatic. Very acidic.
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 softerer. 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.
SOLAR HEATING SYSTEM
Typically, this consists of panels or coils of plastic or metal through which water passes to increase the temperature from the sun’s radiant heat.
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 superchlorination 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.
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.
SUPERCHLORINATION
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 colours to determine concentration.
TOTAL ALKALINITY
The total amount of alkaline materials present in the water. Also called the buffering capacity of the water. It is the water’s resistance to change in pH. Low total alkalinity causes metal corrosion, plaster etching and eye irritation. High total alkalinity causes scale formation, poor chlorine efficiency and eye irritation.
TOTAL CHLORINE
The amount of chlorine, both free and combined in the pool water that is available to sanitize or disinfect the water.
TOTAL DISSOLVED SOLIDS
Total Dissolved Solids – Also called TDS – A measure of the total amount of dissolved material in the water. It is comprised of the spent or carrier chemicals added every time chemicals are added, as well as the hardness, alkalinity, chlorides, chlorides, sodium, magnesium, calcium, etc. Maximum amount in pools is 2500 ppm. Maximum in spas is 1500 over starting TDS. The only way to effectively lower TDS is to drain part or all of the water and replace it.
TRICHLOR
A slow-dissolving, tableted or granular, stabilized organic chlorine compound provid- ing 90% available chlorine. Used for regular chlorination but must be dispensed using a floating feeder or an in-line feeder (chlorinator). Trichlor contains an ingredient (cyanuric acid or stabilizer) that prevents the chlorine from being destroyed by the ultraviolet (UV) rays of the sun. Tri-chlor has a pH of 2.8, and regular trichlor tabs should not be placed in the skimmer as the low pH will corrode the metal components in the equipment.
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 (usually in hours) required to circulate a volume of water equal to the volume of water contained in the pool or spa. Pool capacity in gallons, divided by pump flow rate in gallons per minute (gpm), divided by 60 minutes in 1 hours, will give hours for 1 turnover.
VACUUM
This term can be used to define any number of 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. It must be moved about by a person, and debris is collected in the filter.
VENTURI
A fitting or device that consists of a tube constricted in the middle and flared on both ends. A fluid’s velocity will increase and a fluid’s pressure will decrease while passing through the constriction. Placing a tube or pipe at the constriction point creates a vacuum. Fluid or air can then be drawn in through the tube. A hydro-therapy jet draws air in and mixes it with the water using this principle.
VINYL LINER
The vinyl membrane that acts as the container to hold or contain the water.
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 skimmer weir – Part of a skimmer that adjust automatically to small changes in water level to assure a continuous flow of water to the skimmer. The small floating “door” on the side of the skimmer that faces the water over which water flows on its way to the skimmer. The weir also prevents debris from floating back into the pool after the pump shuts off.
pH
Potential Hydrogen – Indicates the level of acidity or alkalinity of water on a scale ranging from 0-15. A low pH causes etched plaster, metal corrosion and eye irritation. A high pH causes scale formation, chlorine inefficiency and eye irritation. The ideal range for pH in swimming pools is 7.4 to 7.6.
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 chlorine should be kept between 1.0 and 3.0 ppm; total alkalinity should be between 80 and 120 ppm; and and water hardness should be between 200 and 400 ppm. See Also MGL.
psi
An abbreviation for pounds per square inch.
