Pool, Spa + Wellness Glossary
61 essential terms for pool owners, builders, and wellness suite buyers.
- Alkalinity
- Total alkalinity is a measure of bicarbonate, carbonate, and hydroxide ions in pool water. Target range: 80 to 120 ppm. Acts as a pH buffer.
- Anti-vortex drain
- A pool main drain cover engineered to prevent suction entrapment. Required under the Virginia Graeme Baker Pool and Spa Safety Act (VGBA).
- Backwash
- The process of reversing flow through a sand or DE filter to flush trapped debris out to waste.
- Balance
- Pool water is balanced when pH (7.2-7.8), alkalinity (80-120 ppm), calcium hardness (200-400 ppm), and stabilizer (30-50 ppm) are all in range.
- Bond beam
- The reinforced concrete top edge of a gunite pool that supports the coping and tile line.
- Bromine
- Alternative sanitizer to chlorine. Common in indoor pools and spas. More stable at higher temperatures than chlorine.
- CYA (cyanuric acid)
- Pool stabilizer that protects free chlorine from UV degradation. Target: 30-50 ppm. Required outdoors, banned indoors.
- Cartridge filter
- Pleated polyester or paper filter element inside a tank. Cleaned by hosing off. Replaced every 3-5 years.
- Chemical feeder
- Device that automatically doses chlorine, bromine, or salt into pool water.
- Chlorine generator
- See: salt chlorine generator. Produces chlorine on demand from dissolved salt.
- Coping
- The cap stone or material at the top edge of the pool wall. Travertine, limestone, brick, or cast concrete most common.
- DE filter
- Diatomaceous earth filter. Highest filtration quality (down to 3 microns). Requires DE powder recharge after backwash.
- Diving board
- Spring board mounted at the deep end. Most municipal codes now require 8-foot minimum depth under the board.
- Equipment pad
- The concrete slab housing the pump, filter, heater, chlorinator, automation, and valving.
- Fiberglass pool
- One-piece pre-manufactured shell dropped into excavation. 1-3 week install.
- Filter media
- The filtering substance: cartridge (pleated), sand (silica), or DE (diatomaceous earth).
- Free chlorine
- The available, sanitizing chlorine in pool water. Target: 1-3 ppm.
- Gunite
- Sprayed concrete pool construction. Steel rebar + shotcrete + plaster finish. 8-14 week build.
- Hardness
- Calcium hardness. Target: 200-400 ppm. Low hardness corrodes plaster and metal; high hardness causes scaling.
- Heat pump
- Electric pool heater that pulls heat from ambient air. Most efficient in temperatures above 50 degrees.
- Infinity edge
- Pool that spills over one or more sides into a catch basin, creating the illusion of merging with the horizon.
- Jandy
- Pool equipment brand owned by Fluidra (Zodiac). Pumps, heaters, automation, salt systems.
- Kreepy Krauly
- Suction-side automatic pool cleaner. Made by Pentair.
- Lap pool
- Long narrow pool (typically 40-75 feet) designed for daily swimming.
- LSI (Langelier Saturation Index)
- Numerical scale predicting whether water is corrosive (negative) or scale-forming (positive). Target: -0.3 to +0.3.
- Main drain
- Bottom suction outlet. Required to meet VGBA anti-entrapment standards.
- MAP-style cleaner
- Microprocessor-controlled robotic pool cleaner.
- Marcite
- Traditional white pool plaster. 8-12 year lifespan.
- Multi-port valve
- 6 or 7 position valve on top of a sand or DE filter (filter, backwash, rinse, waste, recirculate, closed).
- Negative edge
- See: infinity edge.
- Ozone
- Supplemental sanitizer. Ozone destroys chloramines and reduces chlorine demand.
- pH
- Acidity or alkalinity of pool water. Target: 7.2-7.8.
- Pebble Tec
- Premium exposed-aggregate pool finish. 20-25 year lifespan.
- Pentair
- Pool equipment brand. Pumps (IntelliFlo), heaters (MasterTemp), automation (IntelliCenter), salt (IntelliChlor), lights (IntelliBrite).
- Perimeter overflow
- Pool that spills over all four sides into slot drains. Highest-end pool style.
- Plaster
- Cement and marble dust finish applied over gunite. White plaster (marcite) is most common.
- Pool cover
- Mesh, solid, or automatic safety cover. Auto-covers run $14,000-$28,000 installed.
- Pool light
- Underwater niche-mounted color LED or single-color light. Most modern installs use Pentair IntelliBrite or Hayward ColorLogic.
- Pop-up cleaner
- In-floor cleaning system with rotating pop-up heads embedded in the pool floor.
- Pump
- Heart of the circulation system. Variable-speed (VS) pumps required on most new builds since 2021.
- Quartzite finish
- Quartz-enhanced plaster. Smoother than aggregate, harder than marcite.
- Raised spa
- Spa built above pool deck level with a spillway returning water to the pool. Most popular wellness integration.
- Return jet
- Wall fitting that returns filtered water to the pool. Typically 3-5 per pool.
- Salt cell
- Electrolytic plates inside a salt chlorine generator. Lifespan: 4-7 years.
- Salt chlorine generator
- Device that converts dissolved salt into chlorine via electrolysis. Pentair IntelliChlor, Hayward AquaRite, Jandy AquaPure are the dominant brands.
- Sand filter
- Filter using silica sand as the media. Requires backwashing weekly. Sand change every 5-7 years.
- Shock
- Adding a heavy dose of chlorine (typically 10x normal) to oxidize chloramines and kill algae.
- Skimmer
- Surface debris collector at the water line. Most pools have 1-2 skimmers.
- Spillway
- Stone, tile, or fiberglass channel that returns spa water to the pool.
- Stabilizer
- See: CYA. Cyanuric acid.
- Sun shelf
- Shallow (typically 9-12 inch) tanning ledge inside the pool for lounging.
- TDS (total dissolved solids)
- Sum of all dissolved minerals, salts, and chemicals. Target: under 1500 ppm fresh, under 4500 ppm salt.
- Tile line
- Decorative waterline tile that prevents staining at the air-water interface.
- UV system
- Ultraviolet light supplemental sanitizer that destroys chloramines and reduces chlorine demand.
- Vacuum head
- Manual pool vacuum that connects to the suction line.
- Variable speed pump (VS)
- Pool pump with electronically variable RPM. Required by federal DOE rule on most pumps since 2021.
- Vinyl liner
- Custom-cut vinyl sheet that lines a polymer or steel-wall pool. Replaced every 8-12 years.
- Waterfall
- Recirculating water feature that drops water from elevated weir into the pool.
- Weir
- The dam-like edge that creates a controlled waterfall flow.
- Whirlpool
- Older term for a hot tub or spa with circulation jets.
- Zinc anode
- Sacrificial anode bolted to the equipment pad to prevent galvanic corrosion of metal pool components.