Key Terms

Acid: A liquid or dry chemical that lowers pH when added to water, such as muriatic acid.

Acid demand: The amount of acid required (demanded) by a body of water to lower the pH to neutral (7.0)

Acidity: The quality, state, or degree of being acid.

Acid wash: The procedure of cleaning plaster with a solution of muriatic acid and water.

Adaptor bracket: The part of a pump that supports the motor and connects the motor to the pump.

Aggregate: The major component of plaster composed of sand, marble dust, pebbles, or other solid matter.

Air relief valve: A valve on a filter that permits air to be discharged from the freeboard.

Algae:  Airborne, microscopic plant life of many forms that grow in water and on underwater surfaces.

Algicides: A group of chemical substances that kill algae or inhibit their growth in water.

Algistat: A chemical that inhibits the growth of algae.

Alkalinity: The characteristic of water that registers a pH above neutral

Aluminum sulfate: Alum. An additive for sand filters that prevents the sand from combining, hardening, and thus not filtering impurities from water.

Ammonia: Natural substance composed of nitrogen and hydrogen that readily combines with free chlorine in water forming chloramines (weak sanitizers).

Antivortex: The property of a plumbing fitting that prevents a whirl-pool effect when water is sucked through it. Used on main drain covers.

Backwash: The process of running water through a filter opposite the normal direction of flow to flush out contaminants.

Bacteria: Any of a class of microscopic plants living in soil, water, organic matter, or in living beings and affecting humans as chemical reactions or viruses.

Balance: The term used in water chemistry to indicate that when measuring all components together (pH, total alkalinity, hardness, and temperature) the water is neither scaling, nor etching.

Base:  An alkaline substance.

Bather:  Any person using a pool or spa.

Bicarbonate or soda: A chemical used to raise pH and total alkalinity in water. Also called bicarb or baking soda.

Bleed: To remove the air from a pipe or device, allowing water to fill the device.

Blister: Refers to an air pocket in a plaster surface.

Blow bag: Also called a drain flush or balloon bag. A device attached to a garden hose that expands under water or air pressure to seal an opening, forcing the air or water into that opening.

Blower: An electromechanical device that generates air pressure to provides spa jets and rings with bubbles.

Booster pump: A pump added to a spa system to add pressure to the jets.

Bridging: The condition existing when DE and dirt closes the intended gaps between the filter grids in a DE filter, reducing the flow rate through the filter and reducing the square footage of filter area.

Bromine (Br2): A water sanitizing agent. A member of the halogen family of compounds.

Calcium: A mineral element typically found in water.

Calcium bleed: The condition in plaster where calcium leeches from the mixture.

Calcium  carbonate (CaCO3): The mineral precipated out of water, deposited on pool and spa surfaces, the major component of scale.

Cam lock: The device that holds or releases two halves of a telepole.

Cartridge: The element in a filter covered with pleats of fabric to strain impurities from water that passes through it. Generally strains out particles larger than 20 microns.

Centrifugal force: The outward force created by an object in circular motion. The force that is used by water pumps to move water.

Channeling: Creation of a tube or channel in a filter media through which water will flow unfiltered. Channeling is caused by calcification of the media (hardening of the sand in a sand filter, for example) and is resolved by breaking up the sand and treating it with alum.

Chloramine: A compound of chlorine when combined with inorganic ammonia or nitrogen. Chloramines

Chlorine (Cl2): A substance made from salt that is used to sanitize water by killing bacteria. A member of the halogen family, chlorine is produced in gas, liquid, and granular form.

Chlorine demand: The amount of chlorine required (demanded) by a body of water to raise the chlorine residual to a predetermined level.

Chlorine, free available: The portion of chlorine in a body of water that is immediately capable (available) of oxidizing contaminants.

Chlorine residual: The amount of chlorine remaining in a body of water after all organic material (including bacteria) has been oxidized, expressed in parts per million. The total chlorine residual is the sum of all free available chlorine plus any combined chlorine (chloramine).

Conditioner: A chemical that slows the decomposition of chlorine from ultraviolet light. Conditioner usually cyanuric acid, also helps spiking of pH between high and low extremes.

Cyanurates: Chlorine sanitizers combined with stabilizers, such as dichlor and trichlor.

Diatomaceous Earth (DE): A white, powdery substance composed of tiny prehistoric skeletal remains of algae (diatoms), used as a water filtration media in DE filters. DE filters can remove particles larger than 5 to 8 microns.

DPD: Diethy phenylene diamene. The chemical reagent used to detect the presence of free available chlorine in a body of water.

Energy efficient: A specific design of pool and spa motors that have heavier wire in the windings to lower the electricity wasted from heat loss.  

Equalizer line: A pipe that balances the flow of water between two locations.  Usually found in a pool skimmer, the equalizer line allows the suction line to draw water directly from the pool in the event that the water level drops below the point where suction would normally occur from the surface.

Etching: Corrosion of a surface by water that is acidic or low in total alkalinity and/or hardness.

Ethylenediamine tetra-acetic acid (EDTA): A reagent used for testing calcium hardness, added a drop at a time until the solution turns blue.  The number of drops is compared to a chart to evaluate the hardness of the sample.

Fill water: Water added to a pool or spa to replace water lost to evaporation or other reasons.  Also called make-up water.

Filter: A device for straining impurities from the water that flows through it.

Filter filling: The technique used to prime a pump by filling the filter with water and allowing it to flow backwards into the pump.

Flapper gate: The part in a check valve that swings open when water is flowing in the intended directions but swings shut when water attempts to flow backward.

Floater: A chemical feeder system whereby a sanitizer tablet is placed in the device and is allowed to float around the body of water.  The tablet dissolves and sanitizer is released into the water.

Float valve: A plumbing device that restricts or shuts off the flow of water based on a level that is attached to a float and that thereby rises and falls with the water level.

Flocculate: The process of adding a chemical to a body of water which combines with the suspended particulate matter in the water, creating larger particles that are more easily seen and removed from the water.  Also called a clarifying agent or coagulant.

Gasket: Any material (usually paper or rubber, but sometimes caulk or other pastes) inserted between two connected objects to prevent leakage of water.

Grid: Frame covered with fabric used as a filter media; also called septa or element.

Gunite: A dry mixture of cement and sand that is mixed with water at the job site and sprayed onto contoured and supported surfaces to build a pool or spa, creating the shell.

Halogens: A family of oxidizing agents including chlorine, bromine, iodine, and fluorine.

Hardness: Also called calcium hardness.  The amount of dissolved minerals (mostly calcium and magnesium) in a body of water.

Heater:  A device that raises the temperature of water using natural gas, electricity, propane, solar, or mechanical energy for fuel. To be called a heater, the device must covert at least 70 percent of its fuel into heat (no more than 30 percent lost in venting).  Over 80 percent efficiency, the device is typically called a boiler.

Heat exchanger: The copper tubing in a heater through which water flows.  The water absorbs rising heat that is generated from the burner tray below.

Heat pump: A type of pool and spa heater.  Like conventional heaters, the heat pump circulates water through the unit and transfers heat to the water from a fuel. Instead of using gas, electricity, or solar heat as a fuel, the heat pump takes warmth out of the air that is created by compressing a gas.

High-rate sand filter: A filter using sand for the filtration media designed for flows in excess of 5 gpm but less than 20 gpm (less that 15 gpm in some codes) per square foot.  Strains impurities larger than 50 to 80 microns.

Hydrochloric acid (HCL): Muriatic acid.

Leafmaster: A brand name; leafmaster is a term applied to any device that vacuums large debris from a pool by means of water pressure created with a garden hose.

Leaf rake: A large open net secured to a frame that attaches to a telepole that is used to skim debris from the surface of the water.

Media: Any material used to strain impurities from water that passes through it.  DE and fabric covering a cartridge are both examples of filter media.

Muriatic acid: Also called hydrochloric acid. This chemical is the most commonly used substance for reducing pH and total alkalinity in water.

Neutral: The pH reading at which the substance being measured is neither acidic nor alkaline.  Neutral pH is 7.0.

Open loop: A type of solar heating system that circulates the water being heated from the pool or spa, through the solar panels, and back to the pool or spa.

Organic: Any material that is naturally occurring (not manufactured), such as leaves, sweat, oil, or urine.

O-ring: A thin rubber gasket used to create a waterproof seal in certain plumbing joints or between two parts of a device, such as between the lid and the strainer pot on a pump.

pH: The relative acidity or alkalinity of soil or water, expressed on a scale of 0 to 14, where 7 is neutral, 0 is extremely acidic, and 14 extremely alkaline.

Phaeophyta: Brown or yellow algae.

Phenol red (phenolsulfonephthalein): The most widely used chemical reagent to measure the pH in a sample of water.

Pilot: The small gas flame that ignites the burner tray of a heater.

Pilot generator: The device that converts heat from the pilot light into electricity to power a control circuit on a heater.  Also called a power pile or thermocouple.

Plaster: A hand-applied combination of white cement, aggregates, and additives that covers the shell of a gunite pool or spa to waterproof and add beauty. Plaster can also be colored.

ppm: Parts per million.  The measurement of a substance within another substance for example, 2 ounces of chlorine in 1 million ounces of water would equal 2 ppm.

Precipitate: An insoluble compound formed by chemical action between two or more normally soluble compounds.  When water can no longer dissolve and hold in solution a compound, it is said to precipitate out of solution.

Pressure gauge: A device that registers the pressure in a water or air system, expressed in pounds per square inch (psi).

Pressure sand filter: A type of sand and gravel filter in which the water is strained through the filter media under pressure (as opposed to a free-flow filter).

psi: Pounds per square inch.

Pumice: A natural soft (yet abrasive) stone substance (similar to lava rock) used to clean pool tiles.

Pump: A mechanical device driven by an electric motor that moves water.

Reagent: A liquid or dry chemical that has been formulated for water testing.  A substance (agent) that reacts to another known substance, producing a predictable color.

Residual: The amount of a substance remaining in a body of water after the demand for that substance has been satisfied.

Retaining rod: The metal rod in the center of certain filters on which is attached a retainer ring to hold grids in place.

Retainer: The plastic disc that fits over the top of a set of filter grids to hold them in place with the aid of a retainer rod.

Robotic pool cleaner: A self-contained, electric-powered device that vacuums a pool.

Safety barrier: A fence, wall, or other obstruction around a pool or spa to prevent entry by children or pets.

Salt chlorine generator:  A device that converts salt in pool water into chlorine by means of an electrolytic process.

Sand filter: A filtration device using sand as the filter (straining) media.

Sanitizer: Any chemical compound that oxidizes organic material and bacteria to provide a clean water environment.

Scale: Calcium carbonate deposits that form on surfaces in contact with extremely hard water.  Water in this condition is said to be scaling or precipitating.

Seal: A device in a pump that prevents water from leaking around the motor shaft.

Sight glass: A clear glass or plastic section of pipe that allows viewing of the water in the line.  Used when backwashing filters to know when the discharge water is clean.

Silica: The type of sand used in filters and concrete, actually quartz.  The size of grain is measured and numbered, as in #20 silica sand.

Skimmer: A part of the circulation system that removes debris from the surface of the water by drawing surface water through it.

Soda ash (Na2CO3): Sodium carbonate.  A white powdery substance used to raise the pH of water.

Sodium dichloro-s-triazinetrione (C3N3O3CL2NA): Dichlor. A granular, stabilized form of chlorine sanitizer, generally about 60 percent available.

Soft water: So-called soft water is very low in calcium and magnesium (less than 100 pp,) and is therefore considered aggressive or hungry and likely to dissolve those minerals with it comes in contact with plaster.

Solar panel: A metal, glass, or plastic enclosure, usually 4-by-8 feet by a few inches thick, through which water flows absorbing heat from the sun.  The basic component of a solar heating system.

Stabilizer: Any compound that tends to increase water’s resistance to chemical change.

Strainer basket: A plastic mesh container that strains debris from water flowing though it inside the strainer pot.

Strainer pot: The housing on the intake side of a pump that contains a strainer basket and serves as a water reservoir to assist in priming.

Submersible pump:  A pump and motor that can be submerged to pump out or recirculate a body of water.  Also called a sump pump.

Tear down: To disassemble a piece of equipment for service or repair. Specifically used in reference to filter cleaning (as opposed to backwashing or other temporary cleaning), a filter teardown means complete disassembly and cleaning. Also called break down.

Telepole: A metal or fiberglass pole that extends to twice its original length, the two sections locking together. The telepole is used with most pole and spa cleaning tools i.e. (net, brush, vacuum).

Thermostat: A part of the heater control circuit. An adjustable device that senses temperature and can be set to break the circuit when a certain temperature is reached. It then closes the circuit when the temperature falls below that level.

Three-port valve: A plumbing fitting used to divert flow from one direction into two other directions.

Time clock: An electromechanical device that automatically turns an appliance on or off at preset intervals.

Titration: A chemical test method to determine the amount of a substance in a sample of water.  A sample is colored, then drops of the titrant are added to the sample.  When the sample turns clear or changes to another predicted color, the result of the test is determined by counting the number of drops of titrant that were required to create that change.  For example, an acid demand test is performed with titration.  The number of drops of titrant required in that test determines the amount of acid to add to the water.

Total alkalinity: The measurement of all alkaline substances (carbonates, bicarbonates, and hydroxides) in a body of water.

Total dissolved solids (TDS): The sum of all solid substances dissolved in a body of water, including minerals, chemicals, and organics.

Turbidity: cloudiness.

Vacuum: A device used to clean the underwater surface of a pool or spa by creating suction in a hose line.

Valve: A device in plumbing that controls the flow of water.

Water feature: A fall, rockscape, or other decorative design using moving water.

Weir: The barrier in a skimmer over which water flows.  A floating weir raises and lowers its level to match the water level in a pool or spa.  Another type is shaped like a barrel and floats up and down inside the skimmer basket.



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