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Water Chemistry Dictionary

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ACID: Liquid (muriatic acid) or dry granular (sodium bisulfate) substance used to lower the pool's pH (toward a more acidic condition) or to lower total alkalinity levels.

ACID DEMAND: A titration test used to determine proper amounts of acid (or pH decreaser) to reach correct levels. For example, to lower pH from 8.0 to 7.6, your pool may "demand" 2 qts of acid.

ALGAE: Over 20,000 species known to man! Algae may form on your pool surfaces or it may bloom in suspension. We typically know algae to be green, but it may also be yellow (mustard algae), black, blue-green or any shade in between. It may form separate spots, or seem to grow in sheets. Pink algae, is not algae at all, but a form of bacteria. Algae are living, breathing organisms that need warmth, sunlight and CO2 to thrive.

ALGAECIDE: Meaning: to kill algae. Algaecides perform best as a backup to a routine sanitation program. They also help to kill airborne spores as they blow into the pool. A variety of algae treatment products are available including copper and silver compounds, poly-quat compounds, chlorine enhancers , and herbicides.

ALGAESTAT: An algaecide kills algae, while an algaestat retards and prevents its genesis and growth.

ALKALINITY: Alkaline refers to the condition where the water's pH is above 7.0 (neutral) on the pH scale. It is the opposite of acidic. Alkalinity is the amount of carbonates and bicarbonates in the water, measured in ppm of Total Alkalinity.

ALUMINUM SULFATE: Also known as alum, this product is used as a flocculant which attracts suspended particles in the water together (green or cloudy pools). Alum sinks everything to the bottom, which is then vacuumed up. A small amount of alum can also be used as a sand filter additive.

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BACTERIA: From a health perspective, the most dangerous micro-organisms which may be living in the pool water. Some are pathogens, which can cause infectious diseases.

BACTERICIDE: Kills bacteria. Chlorine is a bactericide and germicide. Silver "algaecides" are actually more bactericide, and are useful on pink "algae".

BALANCED WATER: Balanced water is the result when all of your chemical parameters are where they should be, and thus "balance" each other. The key components of water balance are pH, Total Alkalinity, Calcium Hardness and Temperature, as measured using the Langelier Index of water balance.

BASE: Those chemicals of alkaline nature which will counteract the pH of an acid, eventually neutralizing at 7.0. Common bases used around the pool would include Soda Ash, Sodium Bicarbonate, Sodium Carbonate and Sodium Sesquicarbonate.

BASE DEMAND: A titration test used to determine proper amounts of base (pH increaser) to reach correct levels. For example, to raise pH from 7.2 - 7.6, your water may "demand" 1 lb. of soda ash.

BIGUANIDES: The name for a certain class of sanitizers using the polymer PHMB, the only non-halogensanitizer available for pool and spa use. Soft Swim and Baquacil are manufacturers of this technology.

BREAKPOINT CHLORINATION: When you shock your pool, the goal is to reach a high enough level of free chlorine, measured in ppm, to break apart molecular bonds, specifically the combined chlorine molecules. When breakpoint is reached with sufficient additions of chlorine, everything in the pool is oxidized.

BROMAMINES: A combined bromine - ammonia molecule. Unlike chloramines, which are strong smelling and offer no sanitizing properties, bromamine compounds continue to sanitize.

BROMINE: A member of the halogen family, commonly used as a sanitizer in spas, because of its resistance to hot water with rapid pH fluctuations.

BUFFER: A base such as Sodium Bicarbonate (Baking Soda), added to your pool will increase alkalinity which increases the buffering capacity of the pool; or, your pool's resistance to pH change.

BUFFERING CAPACITY: The ability of the pool to resist changes in pH, which prevents water balance. The buffering capacity is given by the alkalinity, closely related to pH. If your pH bounces, or resumes previous levels soon after adjustment, your buffering capacity is too low. Check your total alkalinity.

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CALCIUM CARBONATE: Known as scale, crystalline deposits of calcium may form on your pool surfaces, equipment, or even line your pipes. Properly balanced water can prevent this.

CALCIUM CHLORIDE: The flaked calcium salt used to raise levels of Calcium Hardness in your pool water. Also good for snow melting.

CALCIUM HARDNESS: A titration test is used to determine levels of the mineral calcium dissolved in the pool water.

CARBON DIOXIDE: A gas, which when present in the water, provides necessary food for the growth of algae.

CARBONATE: Primary in the make up of total alkalinity and TDS.

CHITIN: A naturally occurring polymer found in the shells of crabs and lobsters. Chitin acts as a coagulant and flocculent for oils, metals and organic materials.

CHELATOR: A chelating agent is a water soluble molecule that can bond tightly with metal ions, keeping them from coming out of suspension and depositing their stains and scale onto pool surfaces and equipment. They are similar to sequestering agents.

CHLORAMINES: The chlorine molecule is strongly attracted to nitrogen and ammonia. When these two hook up, they form a chloramine, which are undesirable, foul smelling, space taking, compounds that require shocking / oxidizing the pool water to get rid of.

CHLORINE: A member of the halogen family of sanitizers, it's use in swimming pools is in the elemental form of a gas, or as a liquid, granular or tablet compound. When added to water it acts as an oxidizer, sanitizer, disinfectant and all around biocidal agent.

-Free available chlorine is that which is active, not combined with an ammonia or a nitrogen molecule, and ready to react to destroy organic material.

-Combined Chlorine is that portion of total available chlorine left over when free available is subtracted. The measure of chlorine which has already attached itself to other molecules or organisms. Most of this is made up of chloramines.

-Total available Chlorine is the sum of combined and free chlorine levels. With a DPD test kit, one determines free available level, then total available. The difference, if any, is the level of combined chlorine.

CHLORINE DEMAND: The quantity of free available chlorine removed during the process of sanitizing. The amount of organic and non organic material contained in the water will "demand" a certain level of sanitizer to be destroyed.

CLARIFIER: A clarifier is a chemical used as a coagulant of suspended microparticles. Helps the filter by clumping smaller particles into sizes large enough to be caught in the filter.

COAGULANT: The properties of a chemical used in the assemblage and precipitation of suspended material which may make the pool appear cloudy.

CONTAMINANTS: Any microparticle or organism which reduces water clarity or quality or presents health hazards. All of our filtering, circulating and sanitizing is directed here.

COPPER: An effective algaestat and algaecide, elemental copper is used in many pool products.

COPPER SULFATE: Similar to aluminum sulfate, this chemical provides a coagulating and flocculent function in water. Used in ponds. This amount of copper would stain swimming pools.

CONDITIONER: Also called Cyanuric Acid (CYA) or stabilizer, this chemical provides a shield from the sun around the chlorine molecule, extending the effective life of your chlorine.

CORROSION: The effects of a acidic pool environment, one in which the pH and/or alkalinity are very low. Corrosion in the form of etching, pitting or erosion of pool equipment and surfaces is the result.

CYANURIC ACID: A granular chemical added to the pool water which provides a shield to chlorine for protection from UV radiation, which disrupts the molecule, destroying its sanitizing ability.

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DISINFECTANT: Chemicals or processes which work to destroy vegetative forms of microorganisms and other contaminants. Examples are chlorine, bromine, and copper and silveralgaecides.

DIRECTIONS: Always read them before using any chemicals.

DPD: A method of testing for chlorine levels in the pool water. Unlike OTO, DPD testing allows determination of total and free available chlorine levels, which, through subtraction, gives us combined levels.

DRY ACID: Sodium bisulfate, a granular form of acid , used to lower pH and alkalinity in the water. Safer and less caustic than muriatic acid. Usually available as a "pH decreaser."

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EFFICACY: The power to produce an effect. Chlorine's efficacy is affected by many factors, including the sun, water balance and the water's chlorine demand.

ENZYMES: Used in swimming pool formulations designed to break down and digest oils in a pool or spa similar to the way enzymes are used in oil spill clean-up efforts.

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FILL WATER: Used in filling or adding to the water level. Whether from the hose or from a well, your fill water brings its own chemical make up and water balance.

FOAMING: A term used to describe surface foam on your water, especially in spas/hot tubs. Foaming is caused by high TDS levels working in combination with soft water and oils. Certain low grade algaecides can foam when added to pool or spa. Use enzymes for foam control.

FLOCCULANT: Essentially the same as a coagulant, this chemical (such as alum) is used to combine suspended alkaline material and/or algae into a heavy gel, which sinks to the bottom for vacuuming.

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HALOGEN: A member of the family of elements fluorine, bromine, chlorine and iodine.

HARD WATER: That water which is high in calciumhardness and other salts which, as such, resists soaps ability to form a lather.

HYPOCHLORITE: A family of chlorine compounds such as Calcium Hypochlorite and Lithium Hypochlorite, both granular, and the liquid Sodium Hypochlorite. When these compounds contact water, they release Hypochlorous Acid, the active sanitizing agent.

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IONIZER: An ionizer is a device mounted on your return line, and through which water flowing will receive charged metal ions. Manufacturers may use a copper anode and/or silver. Copper is an algaecide and algaestat, while silver is known for its properties as a bactericide.

IRON: Usually introduced into the water from iron plumbing or from well water, Ferric Iron can stain surfaces, while Ferrous Iron will turn your water a clear green color.

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LANGELIER INDEX: Also called the Saturation Index, Mr. Langelier devised a system to determine water balance by assigning values to levels of pH, Total Alkalinity, Calcium Hardness and water Temperature. When all parameters are in balance, the water will neither be corrosive or scaling.

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MINERALS: Such as Calcium, Manganese, Magnesium, Nickel, Copper, Silver, Iron, Cobalt or Aluminum. Their presence in high non-chelated concentrations can lead to stains & scale when conditions are right.

MICROORGANISM: A living, breathing creature in your pool. The purpose of disinfectants are to remove such "infectants".

MURIATIC ACID: The liquid dilution of Hydrochloric Acid used to lower pH and alkalinity, and to remove mineral stains and scale. Extremely caustic and corrosive.

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NASCENT OXYGEN: A single oxygen atom, not yet bonded to anything. Extremely powerful oxidizer when harnessed.

NITROGEN: When combined with chlorine, nitrogen creates chloramines, which do not belong in our pool. Nitrogen can be found in many swimmer wastes (perspiration, suntan oil, hair tonics, etc.) or be introduced by other means.

NON-CHLORINE SHOCK: A granular form of potassium permonosulfate, used to oxidize materials such as microorganisms, contaminants or chloramines.

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OTO: Another method of testing for free available chlorine levels in your pool, as in an OTO test kit.

OXIDATION: The "burning up" of organic waste and compounds in the pool water. It also refers to what you may see on your metal pool surfaces if your water is corrosive. Rust is a form of this kind of oxidation.

OZONE: The molecule containing three atoms of oxygen; known to be a very powerful sanitizer and oxidizer. Ozone producing equipment creates this molecule by UV radiation or coronal discharge generators.

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pH: The scale of relative acidity or alkalinity, expressed in logarithmic numbers from 0 - 14, with 7.0 being neutral. What's really being measured is the hydrogen ion concentration. Some would say pH stands for Power of Hydrogen.

POTASSIUM PERMONOSULFATE: See non-chlorine shock.

PPM: Parts per million. A method of assigning value to certain concentrations of chemicals in the water. For example, alkalinity should be kept at 80-120 parts per million, by weight and in relation to the water it's dissolved in.

PRECIPITATION: To precipitate is to come out of solution; become insoluble by result of chemical action. Material forced out of solution, purposefully or accidentally, will then settle, stain or scale, or remain suspended in the water.

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QUATERNARY AMMONIUM COMPOUND: A type of algaecide composed of ammonia compounds. Effective algaestat for green and blue/green algae.

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REAGENT: The chemical indicators used in testing water balance. (All the little bottles or tablets in a test kit).

RESIDUAL: Usually refers to free availablechlorine levels remaining in the pool after initial treatment or activity with contaminants.

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SALT: Sodium Chloride. Used in Salt Systems / Chlorine Generators. The salt can be transformed into chlorine for use in sanitizing water.

SANITIZER: A chemical agent used to remove unwanted contaminants.

SCALE: Usually whitish in color, scale forms on pool surfaces and equipment when mineral salts are forced out of solution. A scaling condition is one in which calcium hardness, pH and/or alkalinity levels are out of balance.

SEQUESTERING AGENT: A sequestering agent ties-up minerals tightly in solution, preventing their precipitation, which colors the water and/or stains the pool. Synonymous to chelators, these are commonly called stain & scale chemicals.

SHOCK: As a noun it loosely describes the products used in shocking, such as hypochlorites, potassium permonysulfate or hydrogen peroxide. As a verb it describes the act of bringing the sanitizer level up so high that breakpoint chlorination is reached. When breakpoint is reached, a "shock" breaks up and removes the unwanted combination of contaminates and chloramines.

SODA ASH: A base, used to counteract an acidic condition by raising pH.

SODIUM BICARBONATE (baking soda): Another base, however its properties will increase alkalinity more than pH. Used to raise Total Alkalinity levels.

SODIUM BISULFATE: A granular form of acid, used to counteract a scaling condition by lowering pH and/or alkalinity.

SODIUM HYPOCHLORITE: Liquid chlorine used in pools, similar to, yet stronger than Clorox bleach.

SODIUM TETRABORATE: New technology that renders algae incapable of processing carbon dioxide, which they need to live.

SODIUM DICHLOR: A granular form of chlorine that is stabilized with cyanuric acid. Used for shocking through superchlorination.

SOFT WATER: Water that has low calcium and/or magnesium content. Soap lathers easily in soft water.

STABILIZER: See Cyanuric Acid. Stabilizers, also called conditioners, can be added directly to your pool to extend your chlorine efficacy. Cyanuric acid is already added to certain "stabilized" products such as Trichlor tablets and Sodium Dichlor.

SUPERCHLORINATION: Applying 7 - 10 times the normal amounts of chlorine to the pool as an added "boost" for contaminant removal. Some refer to superchlorinating as being less than shocking, in that breakpoint thresholds are not reached, or the terms may be used synonomously.

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TITRATION: A method of testing for total alkalinity, calcium hardness and acid/base demand by adding a titrant, drop by drop until a color change is observed.

TOTAL ALKALINITY: The ability of the pool water to resist changes in pH. The "buffering" capacity of the water. Additions of Sodium Bicarbonate will increase the levels, expressed in ppm.

TOTAL DISSOLVED SOLIDS (TDS): A measure of everything that has ever dissolved in the water; all the matter that is in solution. High TDS levels can oversaturate your water, causing all sorts of reactions.

TURBIDITY: Cloudy, dull, hazy water, due to microparticle suspension.

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ULTRA VIOLET LIGHT TREATMENT: Using UV wavelength radiation to destroy contaminants in water. UV light is also used to create ozone molecules for the same purpose.

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