Whether you’re a pool owner, builder, or enthusiast, understanding pool terminology can be overwhelming. This comprehensive glossary will improve your understanding of the components, processes, and care techniques essential for maintaining a safe and enjoyable swimming environment. From filtration systems to water chemistry, this list covers key terms to help you navigate pool jargon with ease.
A
Above Ground Pool: A freestanding pool at ground level, offering a convenient and often more affordable alternative to in-ground pools.
Activated Filter Media (AFM): Engineered filter media made using recycled glass to massively improve the efficiency of water filtration
Air Handling Unit (AHU): Used for indoor pools – this is a type of heat pump that transfers heat from a property’s hot water system to the pool water and to the air within the pool hall and should be set to maintain the air temperature at 1degree higher than that of the pool water (unless covered) to prevent excessive evaporation and condensation. The units also maintain the correct humidity within the pool hall air and provide constant air circulation. They should be serviced regularly by a specialist, ideally every 6 months.
Air blower: A piece of plant that provides forced air within some spa jets
Algae: Microscopic plants that can grow in pools, causing water discoloration and requiring chemical treatment.
Algaecide: A product used to kill and prevent algae growth in pools.
Automatic Pool Cleaner: A device that automatically cleans the pool by vacuuming debris.
B
Backwash: The process of cleaning a pool filter by reversing the water flow to remove debris.
Backwash Tank: A temporary holding facility for backwash effluent that some customers may have if the drains on site require it.
Balance Tank: For deck level and infinity edge pools, this tank holds water to maintain the pool’s water level.
Bromine: A chemical alternative to chlorine used for disinfecting pool water.
C
Calcium Hardness: A measure of the amount of calcium ions in water and a variable that needs to be managed correctly within pool water chemistry.
Cartridge Filter: A type of filter that uses a replaceable cartridge to trap debris.
Chlorine: A chemical used to disinfect pool water, killing bacteria and other harmful organisms.
Coliforms: A type of bacteria that can be harmful and may be found in pool water that is not being correctly maintained or adequately filtered.
Circulation: The movement of water through the pool’s filtration system.
Counter Current: See swim jet
D
Daisy System: A combined filtration system that uses salt hydrolysis
Deck: The area surrounding the pool, often made of concrete, wood, stone.
Diatomaceous Earth (DE) Filter: A type of pool filter that uses a fine powder to trap debris.
Diving Board: A platform used for diving into the pool.
E
Effluent: Water that flows out of the pool’s filter during the backwashing process.
Electrolytic Chlorinator: A device that generates chlorine from salt added to pool water.
Enclosure: A structure that surrounds the pool, providing protection and privacy.
Essence: A fragrant liquid that is injected into the steam that is produced in a steam room to enhance the relaxational experience.
F
Filter: A device that removes debris and impurities from pool water.
Flocculant: A chemical that causes fine particles to clump together for improved filtration.
Flow Rate: The rate at which water moves through the pool’s filtration system.
G
Gunite: A type of concrete used to construct pools.
H
Heat Pump: This heating system extracts heat from the air to warm the pool water, providing a cost-effective and environmentally friendly way to maintain a comfortable swimming temperature.
Hydrochloric Acid: A chemical that may be used to lower the pH of pool water.
Hydrostatic Relief Valve – A sprung valve usually located within the pool sumps to help safeguard the pool shell against excessive ground water pressures when the pool is emptied
Hypo – A commonly used abbreviation for Sodium Hypochlorite – a liquid chlorine used in automatic dosing systems.
I
Impeller – A fundamental component of all centrifugal filter pumps which moves the water.
Infinity Pool: A pool designed with an edge that creates a visual effect of water extending to the horizon, blending seamlessly with the surrounding landscape.
In-ground Pool: An indoor or outdoor pool built into the ground to create a permanent fixture, made from concrete, fiberglass, or vinyl, for example.
Inlet: An opening in the pool wall where filtered water re-enters the pool. Ionizer: A device that uses copper and silver ions to disinfect pool water.
J
Jets: Nozzles that release water into the pool, often used for a massaging effect.
Jacuzzi: A brand name often used to refer to a hot tub or spa.
K
Kickboard: A flotation device used for swim training or exercise, helping swimmers to isolate and strengthen their leg muscles.
Kilowatt Hour (kWh): A measure of energy consumption over time, often used to calculate the operational costs of pool equipment like heaters, pumps, or lighting systems.
Knock-in Fitting: A type of pool fitting that is installed by being hammered into place, commonly used for securing certain plumbing fixtures or pool components.
L
Ladder: A set of steps used to enter and exit the pool.
Laterals: A consumable component within pool filters that allows water to pass through but not the filter media.
Liner: A vinyl or other material that lines the interior of some swimming pools.
M
Main Drain: The suction point located at the deepest part of the pool – sometimes referred to as a sump.
Mineral Sanitizer: A device that uses minerals to help disinfect pool water.
Motorised Valve: A type of electronic valve used on either pool water or hot water systems that is controlled either automatically or by the bather on demand. E.g. honeywell, Jandy
Moving Floor Pool: A pool with a floor that can be raised or lowered to adjust the water depth, offering versatile use.
Multiport: Used on many pool filters this is a multipurpose valve that is used to alter the direction and function of the pool water filtration system
N
Neck Massager: A feature used in some pools or spas that cascades pool water over one’s back and neck.
Noodles: Foam flotation devices used for swimming aid and fun.
Neutralizer: A chemical used to neutralize chlorine or bromine in pool water.
O
OSPA: A type of combined filtration system used to provide optimal water quality
Ozone: A powerful oxidizer used to disinfect pool water.
Overflow: Either the intentional cascading of pool water over an infinity edge or the dispersal of excess pool water to a drain -located within the automatic water top up unit.
P
pH: A measure of the acidity or alkalinity of pool water.
Plant Room: A space that houses essential pool equipment like pumps, filters, heaters, and chemical dosing systems, ensuring efficient operation and maintenance of the pool.
Pressure Test – The testing of pool circulatory pipework to test for integrity and an element of a pool survey
Pump: A device that circulates water through the pool’s filtration system.
Pump Seal: Also known as a mechanical seal, this is a perishable part within a filter pump that prevents water from damaging the mechanical and electrical components of the pump. The need to replace is usually characterized by a noticeable leak from the middle of the pump
Q
Quaternary Ammonium Compounds (Quats): Algaecides are used to prevent and treat algae growth.
R
Redox Probe: A device used in some automatic chemical dosing systems
Return: The point where filtered water is returned to the pool.
Robotic Pool Cleaner: An automated device that cleans the pool floor and walls.
S
Shock: A process of adding a large dose of chlorine to the pool to kill bacteria and algae.
Skimmer: A device that removes debris from the surface of the pool water.
Slats: Modular Polycarboate or PVC sections connected together to form an automatic floating pool cover that when closed helps keep the water clean, safe and insulated.
Sodium Bicarbonate: Sometimes known as baking soda it is used to increase the (total) alkalinity of pool water
Sodium Bisulphate: A commonly used granular acid that is used to lower the Ph of pool water
Sodium Carbonate: Sometimes known as soda ash it is used to increase the pH of pool water
Static Water Test: A method used to monitor water loss in a pool by isolating all plant equipment. This test is conducted alongside a control sample to account for normal evaporation or precipitation values.
Swim Jet: A counter current feature within some pools that one can be used to swim against – especially useful on smaller pools or for those customers who prefer more strenuous swimming
T
TDS (Total Dissolved Solids): A measure of organic or non-organic substances within the water and a variable that needs to be managed within pool water
Top-up: A device used to automatically maintain the correct water level in a pool or balance tank
Torbec Valve: A brand/ type of float valve used in automatic water top-up systems.
Total Alkalinity: A measure of the water’s ability to resist changes in pH.
Turbidity: A measure of how clear the water is
Tile: Ceramic, porcelain, or glass pieces, used to line the pool’s waterline and interior.
TVCs (Total Viable Count): A measure in a laboratory of a substance’s ability to grow microorganisms like bacteria and is used to determine whether pool water is safe to swim in.
U
UV Sanitizer: A device that uses ultraviolet light to kill bacteria and microorganisms.
Underwater Light: Lighting installed below the waterline for illumination and ambiance.
V
Vacuum: A device used to clean the pool floor and walls by suctioning debris. Valve: A device that controls the flow of water in the pool’s plumbing system.
Venturi: The vacuum effect brought about by a sudden acceleration of a fluid and is used in some pool systems to draw in disinfectant.
W
Waterline: The level at which the water meets the pool’s edge.
Winter Care Visit: A periodic maintenance visit for a pool that has been closed for the winter period – recommended for every 6 weeks
Winterising: The process of preparing the pool for winter, including draining and covering.
X
Xeriscaping: Landscaping with drought-resistant plants around the pool area.
Y
Yellow Algae: A type of algae that can be difficult to remove and often requires special treatment.
Z
Zero Entry: A pool design with a gradual slope into the water, mimicking a natural beach.
While this list is not exhaustive, it provides a useful guide to improve your working knowledge of swimming pool design and technical features. By familiarising yourself with these terms, you’re taking an important step towards becoming a responsible pool owner. Remember, a well-maintained pool is not only more enjoyable but also safer for swimmers.
If this is all a bit confusing, Guncast experts would be happy to supply more information on installation and design aspects of indoor and outdoor swimming pools – and offer invaluable advice on maintenance issues and our personalised service options.
