Pool Terminology

Acid: A liquid or dry chemical used to lower the pH and/or alkalinity of pool or spa water.
Acid Wash: A procedure using an acid solution to clean an interior surface of a pool with subsequent neutralization of the acid.
Air Blower: A device that produces a continuous flow of air.
Algae: Minute plant life growing in water in the presence of sunlight and carbon dioxide.
Anti-vortex Drain Cover: A plate or cover that is affixed to the main outlet of a swimming pool or spa that prevents a vortex from forming as water passes through to the main outlet.
Backfilling: Filling space between pool shell and sides of excavation with dirt.
Backwash: Process of running water through a filter opposite the normal direction of flow to flush out contaminants.
Balance: The term in water chemistry to indicate that when measuring all components together, the water is neither scaling nor corrosive.
Ball Valve: A device utilizing a ball-shaped diverter to partially or totally obstruct the flow of water.
Bleeder Valve: A device that allows air to be vented from a system.
Blower: An electromechanical device that generates air pressure to provide spa jets and rings with bubbles.
Bond Beam: Reinforced masonry units designed to resist horizontal forces.
Bonding (electrical): The joining of metallic parts to form an electrically conductive path, which will ensure electrical continuity.
Booster Pump System: A pump that is completely independent of the filtration and heating system. Used to provide support for hydrotherapy jets, cleaning systems and gas chlorinators or special water features.
Break in Grade: Occurs when the slope of the pool floor changes to a greater slope.
BTU: British Thermal Unit. A unit of measurement used to define the capabilities of heaters. One BTU is capable of raising the temperature of one pound of water by one degree Fahrenheit.
Bull Nose: A brick or stone with a rounded corner.
Cantilever: A projecting beam supported only at one end.
Cartridge: Disposable element containing filtering media and used in some pool filters.
Cartridge Filter: A filter that utilizes a porous element that acts as a filter medium.
Check Valve: A valve that permits flow of water or air in only one direction through a pipe.
Chlorine: A substance used to sanitize water by oxidizing (killing) bacteria; generally available in liquid, solid (tablets or sticks), and granular form.
Circuit Breaker: A device designed to open and close an electrical circuit manually, and to open a circuit automatically at a predetermined over current level.
Circulation System: An arrangement of mechanical equipment and/or components designed to ensure even distribution of heat, chemicals, and filtration of water throughout the pool.
Coping: The cap on the wall that provides a finishing edge around the pool/spa.
Cove: The radius that joins the floor and wall of a pool/spa.
Crack (structural): A break or split which weakens the structural integrity of the pool.
Decks: Those areas immediately adjacent to or attached to a pool or spa that are specifically constructed for sitting, standing, or walking.
Deep Area: Water depth areas exceeding five feet (5').
Diatomaceous Earth (DE): A white, powdery substance composed of tiny prehistoric skeletal remains of algae, used as filtration media.
Diatomaceous Earth (DE) Filter: Pool filter using DE as filtering method.
Diverter: Adapter pipe that fits into a skimmer port to facilitate connection of a vacuum hose.
Erosion: Act of destroying or dissolving by slow disintegration or wearing away.
Etching: Corrosion of a surface by water that is acidic or low in total alkalinity or hardness.
Evaporation: Conversion of liquid molecules into vapor.
Feet of Head: The resistance in a hydraulic system based on the equivalent height of a column of water.
Filter: Device for removing suspended particles from pool water.
Filter Cycle: Time of filter operation between backwashes.
Filter Element: A device within a filter tank designed to entrap solids and conduct water.
Filter Media: Fine-grain materials in filter trap matter suspended in pool water.
Flow Rate: The volume of liquid flowing past a given point in a specified time period.
GPD: Gallons per day.
GPH: Gallons per hour.
GPM: Gallons per minute.
Hardness: Amount of dissolved minerals in water.
Heater: A fossil-fueled, electric or solar device to heat pool water.
Hydrotherapy Jet: A fitting that blends air and water creating a high-velocity stream.
Impeller: The rotating vanes of a centrifugal pump.
Influent: The water entering a filter or other device.
Jets: See Hydrotherapy Jets.
Manifold: A pipe with several openings for making multiple connections.
Muriatic Acid: A dilute solution of hydrochloric acid used to lower alkalinity.
O-Ring: Thin rubber gasket used to create a waterproof seal.
Overflow System: Refers to removal of pool surface water through skimmers.
pH: Measure of acidity or alkalinity of water.
PPM: Parts per million.
Plaster: A type of interior finish applied to a concrete pool.
PSI: Pounds per square inch.
Pumice: A natural abrasive stone used to clean pool tiles.
Pump: A mechanical device that causes water flow and pressure.
PVC: Polyvinyl chloride used for pool piping.
Reinforcing Bar (Rebar): Steel bars embedded in concrete.
Return Inlet: The fitting through which water returns into a pool.
Sand Filter: Pool filter using sand as filtering medium.
Scale: The precipitate that forms on surfaces when mineral levels are high.
Screed: Tool used to level concrete.
Shotcrete: A mixture of cement and sand applied to build a pool.
Shocking: See Super-chlorination.
Skimmer: A part of the circulation system that removes debris from the surface.
Slope: An inclined surface.
Strainer Basket: Device used to catch large debris.
Suction Outlet: The fitting through which water is drawn from the pool.
Super-chlorination: Application of high levels of chlorine.
Swimming Load: Number of people using pool at a given time.
Test Kit: Device used to monitor chemical levels.
Three-Port Valve: A plumbing fitting used to divert flow.
Time Clock: A device that controls operating times of pool equipment.
Total Dynamic Head: See Feet of Head.
Turnover Rate: Number of times pool water passes through filter.
Underwater Light: A fixture designed to illuminate from beneath water.
Valve: Device that controls flow of water.
Waterline: Defined level of water in a pool.