Swimming Pool Glossary
MAGNESIUM HARDNESS: A measure of the amount of magnesium dissolved in the water. It is part of total hardness.
MAIN DRAIN: This usually refers to the drain that is located in the deepest part of the pool.
MAKE-UP WATER: Also called top up or refill water. It is the water used to replace water lost to evaporation, splash-out, leaks and backwashing.
MARBELITE: Also referred to as Plaster. It is a mixture of white cement and white marble dust used as an interior finish over the gunite or shotcrete of a pool. It can be given a colour or it may be left white.
MARCITE: See Marbelite
MICRON: A unit of length equal to 1 millionth of a metre. 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 16 microns; and D.E. (diatomaceous earth) filters have openings of 1 to 5 microns. Zeolite used in sand filters have openings of 3 to 6 microns. A grain of salt is between 90 and 110 microns.
MICROORGANISM: An extremely small, living breathing creature. The purpose of disinfectants, sanitisers or oxidisers is to destroy these creatures in the pool water.
MINERAL: Substances such as Calcium, Manganese, Magnesium, Nickel, Copper, Silver, Zinc, Iron, Cobalt or Aluminum. Their presence in high non-chelated concentrations can lead to stains or scale formation. The measure of water hardness is dependent on these minerals.
MULTIPORT VALVE: Also called a 6-way or 6-port valve. Water from the pump can be diverted for various functions by turning the valve handle. The water may: 1. be sent to waste, 2. be used for backwashing, 3. bypass the filter for maximum circulation, 4. filter normally, 5. be used to rinse the filter, or 6. the valve may have all its ports closed. The pump must be off before changing a valve setting.
MURIATIC ACID: Also called liquid acid or hydrochloric acid. A very strong acid used in pools to lower the pH and total alkalinity. It can also be used for cleaning an empty pool (acid washing).
NEUTRALISER: A chemical used to deactivate or destroy chlorine or bromine. It is used in better test kits in order to increase the accuracy of the pool water tests.
NITROGEN: A gas that causes algae to bloom and disables chlorine. It is introduced into the water by rain and by swimmers. Maintaining proper chlorine levels will prevent nitrogen from becoming a problem. Superchlorination can destroy nitrogen and nitrogenous compounds.
NON-CHLORINE SHOCK: A granular form of potassium peroxymonosulfate (potassium monopersulfate, potassium permonosulfate), used to oxidize materials such as microorganisms, contaminants (ammonia, nitrogen, swimmer waste, ...) or chloramines.
ORGANIC: Refers to chemical compounds containing carbon atoms bonded together with other elements. The main groups of organic substances found in water are proteins, carbohydrates, fats and oils.
ORGANIC WASTE: Also called swimmer or bather waste. Refers to the soap, deodorant, suntan lotion, body oils, sweat, spit, urine . . . , that is introduced into the water by swimmers, as well as the leaves, dust and insects that end up in the pool. The organic waste may form undesirable chloramines, which require large amounts of chlorine or non-chlorine shock to be destroyed.
ORP: The abbreviation for Oxidation-Reduction Potential. It is a measurement of the oxidiser's (e.g. chlorine) ability to oxidise contaminants versus the contaminants' (e.g. algae) ability to reduce the oxidiser. It is an indication of the level of free available oxidiser in the water. ORP is generally used with automated dosage systems and can give a fair idea of the sanitation of the water. It is not a measure of the total or available chlorine. Sometimes called Redox Potential.
OTO: The abbreviation for Ortho Tolidine. A chemical reagent used to test the total chlorine level in water at normal temperatures. It can measure free available chlorine if the water is first cooled to 1°C. Its results depend on pH, time and concentration of chlorine. Due to its toxicity, the use of OTO is restricted or prohibited in many western countries.
OXIDATION: The burning up or destruction of organic waste and organic compounds in the pool water.
OXIDISER: Any compound that removes or destroys organic waste and organic compounds in the water.
OZONATOR: An electrical device that produces ozone that is introduced into the water as a sanitiser.
OZONE: A molecule containing three atoms of oxygen. It is known to be a very powerful sanitiser. Ozone producing equipment create this molecule by UV radiation or corona discharge generators.
PATHOGEN: Also called a pathogenic organism. An organism that can cause illness, disease or death.
pH: A term used to indicate the level of acidity or alkalinity of water. A pH of 7.0 is neutral; below 7 is acidic; above 7 is alkaline or basic. pH is a logarithmic expression of the measure of positive Hydrogen ions in water. The ideal range for pH in swimming pools is 7.0 to 7.6. The pH of our tears is 7.2 to 7.4 .
PHENOL RED: A chemical reagent dye used to test pH. It can measure pH from 6.8 to 8.4 . The tablet form usually incorporates a chlorine neutraliser for more accurate results.
PHOTOMETER: An electrical instrument for testing pool water conditions, which measures the colours electronically rather than visually, giving more accurate results.
PLASTER: Also referred to as Marbelite. It is a mixture of white cement and white marble dust used as a finish over the gunite or shotcrete of a pool. It can be coloured or it may be left white.
POLYMER: A large substance comprising of small repeating molecules. Many coagulants are made from organic polymers as are algaecides and algaestats.
POTASSIUM PEROXYMONOSULFATE: See Non-chlorine Shock.
ppm: The abbreviation for parts per million. It is a method of assigning value to concentrations of chemicals in the water. Many of the common pool water tests, as well as acceptable ranges, are stated as ppm. 1ppm = 1 mg/L
PRECIPITATION: To precipitate is to come out of solution or to become insoluble as a result of a chemical reaction. Material forced out of solution will settle, stain, scale or remain suspended in the water.
PRESSURE GAUGE: A gauge with an dial indicating the pressure in a closed container such as a sand filter.
PUMP: A mechanical device which causes water to flow under pressure for the purpose of filtration or circulation.
PUMP CAPACITY: The volume of water a pump is capable of moving during a specified period of time. This is usually given in litres per minute or kilolitres per hour (m3/h).
PUMP CURVE: Also called a Pump Performance Curve. It is a graph that shows a pump's water flow capacity at any given resistance.
PUMP STRAINER BASKET: A device placed on the suction side of the pump, which contains a removable strainer basket designed to trap large debris in the water flow without causing restriction. Sometimes called a Pump Leaf Trap.
QUATERNARY AMMONIUM COMPOUNDS: Also called Quats or QAC. A type of algaecide composed of ammonia compounds. They are also effective algaestats for certain types of algae.
RATE OF FLOW: The volume of water flowing past a point within a specified time. Usually expressed as litres per minute or kilolitres per hour (m3/h).
REAGENTS: The chemical indicators used in testing various aspects of water quality.
REDOX POTENTIAL: The abbreviation for Reduction-Oxidation Potential. It is a measurement of the oxidiser's (e.g. chlorine) ability to oxidise contaminants versus the contaminants' (e.g. algae) ability to reduce the oxidiser. It is an indication of the level of free available oxidiser in the water. ORP is generally used with automated dosage systems and can give a fair idea of the sanitation of the water. It is not a measure of the total or available chlorine. Sometimes called ORP.
RESIDUAL BROMINE: The amount of free available bromine remaining in the water after the bromine demand has been satisfied.
RESIDUAL CHLORINE: The amount of free available chlorine remaining in the water after the chlorine demand has been satisfied.