--- title: "Pool Glossary: 196 Pool and Spa Terms Defined | Marina Pool Services" description: "Plain-English definitions of 196 pool terms: water chemistry, pumps, filters, heaters, salt systems, surfaces, Texas weather and service words." url: https://marinapool.multisites.ai/glossary publisher: Marina Pool Services phone: +1-817-896-1120 quote: https://marinapool.multisites.ai/contact --- # Pool glossary 196 pool and spa terms in plain English, from free chlorine to freeze guard. Chemistry numbers link to their sources. Search the glossary No terms match. Try a shorter word. ## A [Acid wash](https://marinapool.multisites.ai/glossary/acid-wash) An acid wash cleans a plaster pool by removing a thin layer of surface with a diluted acid solution. [Air leak](https://marinapool.multisites.ai/glossary/air-leak) An air leak is a spot where air is sucked into the system, causing bubbles and weak flow. [Air relief valve](https://marinapool.multisites.ai/glossary/air-relief-valve) The air relief valve is a small valve on top of the filter that releases trapped air. [Algaecide](https://marinapool.multisites.ai/glossary/algaecide) Algaecide is a chemical that kills or prevents algae, but it does not replace chlorine. [Automatic pool cleaner](https://marinapool.multisites.ai/glossary/automatic-pool-cleaner) An automatic pool cleaner is a machine that cleans the floor and walls on its own. [Automatic water leveler](https://marinapool.multisites.ai/glossary/automatic-water-leveler) An automatic water leveler is a device that adds fresh water to the pool when the level drops too low. ## B [Backflow](https://marinapool.multisites.ai/glossary/backflow) Backflow is water flowing the wrong way into a clean water supply. [Backwash](https://marinapool.multisites.ai/glossary/backwash) Backwash means reversing flow through a sand or DE filter to flush out dirt. [Black algae](https://marinapool.multisites.ai/glossary/black-algae) Black algae shows up as dark spots with deep roots, often in plaster, and needs hard brushing and treatment. [Bonding](https://marinapool.multisites.ai/glossary/bonding) Bonding is wiring that ties the metal parts around a pool together so they stay at the same electrical potential. [Booster pump](https://marinapool.multisites.ai/glossary/booster-pump) A booster pump is a small extra pump that powers a pressure-side cleaner. [Borates](https://marinapool.multisites.ai/glossary/borates) Borates are a water additive some owners use to buffer pH and help prevent algae. [Breakpoint chlorination](https://marinapool.multisites.ai/glossary/breakpoint-chlorination) Breakpoint chlorination means adding enough chlorine to destroy chloramines and reset the water. [Bromine](https://marinapool.multisites.ai/glossary/bromine) Bromine is a sanitizer often used in hot tubs because it holds up well in heat. [Bucket test](https://marinapool.multisites.ai/glossary/bucket-test) A bucket test compares water loss in a bucket on the pool step with water loss in the pool to spot leaks. ## C [Calcium hardness](https://marinapool.multisites.ai/glossary/calcium-hardness) Calcium hardness is the amount of dissolved calcium in pool water, and it affects scale and surface wear. [Calcium hypochlorite](https://marinapool.multisites.ai/glossary/calcium-hypochlorite) Calcium hypochlorite, or cal-hypo, is a granular chlorine that adds calcium to the water. [Capacitor](https://marinapool.multisites.ai/glossary/capacitor) A capacitor is a part that helps a pump motor start, and a weak one causes humming and no start. [Cartridge filter](https://marinapool.multisites.ai/glossary/cartridge-filter) A cartridge filter uses pleated fabric cartridges that you rinse with a hose or replace when worn. [Cavitation](https://marinapool.multisites.ai/glossary/cavitation) Cavitation is noise and damage caused when a pump starves for water. [Check valve](https://marinapool.multisites.ai/glossary/check-valve) A check valve is a one-way valve that stops water flowing backward. [Chemical surcharge](https://marinapool.multisites.ai/glossary/chemical-surcharge) A chemical surcharge is an extra fee some pool companies add for chemicals. Ask if one applies. [Chemical-only service](https://marinapool.multisites.ai/glossary/chemical-only-service) Chemical-only service is a plan that tests and adds chemicals but does not clean the pool. [Chloramine](https://marinapool.multisites.ai/glossary/chloramine) Chloramines are compounds formed when chlorine bonds with nitrogen from sweat and urine, causing the strong pool smell and eye irritation. [Chlorine demand](https://marinapool.multisites.ai/glossary/chlorine-demand) Chlorine demand is the amount of chlorine the water uses up before any is left to sanitize. [Chlorine floater](https://marinapool.multisites.ai/glossary/chlorine-floater) A chlorine floater is a floating plastic dispenser that holds chlorine tablets and releases them slowly into the pool. [Chlorine lock](https://marinapool.multisites.ai/glossary/chlorine-lock) Chlorine lock is a state where very high cyanuric acid makes chlorine work poorly. [Chlorine odor](https://marinapool.multisites.ai/glossary/chlorine-odor) Chlorine odor is a strong smell that usually signals chloramines, not too much chlorine. [Clarifier](https://marinapool.multisites.ai/glossary/clarifier) A clarifier is a product that clumps tiny particles so the filter can catch them. [Cloudy water](https://marinapool.multisites.ai/glossary/cloudy-water) Cloudy water is hazy water caused by tiny particles, poor filtration, or unbalanced chemistry. [Combined chlorine](https://marinapool.multisites.ai/glossary/combined-chlorine) Combined chlorine is chlorine that has already bonded with sweat, oils, and other waste, so it no longer sanitizes well. [Control panel](https://marinapool.multisites.ai/glossary/control-panel) The control panel is the box or screen where pool equipment is switched and scheduled. [Coping](https://marinapool.multisites.ai/glossary/coping) Coping is the cap along the pool edge where the pool wall meets the deck. [Copper ionizer](https://marinapool.multisites.ai/glossary/copper-ionizer) A copper ionizer is a device that adds copper to the water to slow algae, and chlorine is still needed. [CPO certification](https://marinapool.multisites.ai/glossary/cpo-certification) CPO certification is the Certified Pool Operator credential from the Pool and Hot Tub Alliance. [Cryptosporidium](https://marinapool.multisites.ai/glossary/cryptosporidium) Cryptosporidium is a chlorine-tolerant germ that can cause illness in pools. CDC has guidance on it. [Cyanuric acid](https://marinapool.multisites.ai/glossary/cyanuric-acid) Cyanuric acid, also called CYA, stabilizer, or conditioner, shields chlorine from sunlight. ## D [DE filter](https://marinapool.multisites.ai/glossary/de-filter) A DE filter uses diatomaceous earth powder to catch very fine particles. [Deck-O-Seal](https://marinapool.multisites.ai/glossary/deck-o-seal) Deck-O-Seal is a brand of flexible joint sealant used between pool coping and the surrounding deck. [Delamination](https://marinapool.multisites.ai/glossary/delamination) Delamination is when a pool finish lifts, peels, or sounds hollow as it separates from the shell. [Diagnostic fee](https://marinapool.multisites.ai/glossary/diagnostic-fee) A diagnostic fee is a charge to find a problem. It may or may not be credited to the repair. [Dichlor](https://marinapool.multisites.ai/glossary/dichlor) Dichlor is a fast-dissolving granular chlorine that also adds cyanuric acid to the water with each dose. [Drain cover](https://marinapool.multisites.ai/glossary/drain-cover) A drain cover is the grate over a pool drain. Approved designs help prevent suction entrapment. [Drop test kit](https://marinapool.multisites.ai/glossary/drop-test-kit) A drop test kit uses liquid reagents, such as FAS-DPD, to give more exact water readings than strips. [Drought](https://marinapool.multisites.ai/glossary/drought) A drought is a long dry spell that raises evaporation and water supply concerns. ## E [Efflorescence](https://marinapool.multisites.ai/glossary/efflorescence) Efflorescence is a white, powdery mineral deposit that seeps out of concrete, stone, or grout. [Enzyme treatment](https://marinapool.multisites.ai/glossary/enzyme-treatment) An enzyme treatment is a product that breaks down oils and organic waste in the water. [Equalizer line](https://marinapool.multisites.ai/glossary/equalizer-line) An equalizer line is a pipe that links the skimmer to the pool so the pump cannot run dry if the water drops. [Equipment inspection](https://marinapool.multisites.ai/glossary/equipment-inspection) An equipment inspection is a check that the pump, filter, heater, and controls work as they should. [Equipment upgrade](https://marinapool.multisites.ai/glossary/equipment-upgrade) An equipment upgrade is replacing old equipment with a newer, more efficient model. [Equipment warranty](https://marinapool.multisites.ai/glossary/equipment-warranty) An equipment warranty is the maker's promise to cover defects for a set time. [Etching](https://marinapool.multisites.ai/glossary/etching) Etching is loss of surface material from plaster or tile when the water is acidic or aggressive. [Evaporation loss](https://marinapool.multisites.ai/glossary/evaporation-loss) Evaporation loss is the normal water loss from heat, wind, and sun that is not a leak. [Expansion joint](https://marinapool.multisites.ai/glossary/expansion-joint) An expansion joint is a gap between the pool and the deck that lets each material move without cracking. ## F [Fiberglass pool](https://marinapool.multisites.ai/glossary/fiberglass-pool) A fiberglass pool is a pool made from a one-piece molded fiberglass shell set into the ground. [Fill water](https://marinapool.multisites.ai/glossary/fill-water) Fill water is the tap or well water used to top off the pool, and its chemistry affects the pool. [Filter cleaning](https://marinapool.multisites.ai/glossary/filter-cleaning) Filter cleaning is a deep clean or replacement of filter media so the filter can trap dirt again. [Filter grids](https://marinapool.multisites.ai/glossary/filter-grids) Filter grids are the fabric panels inside a DE filter that hold the powder. [Filter sand](https://marinapool.multisites.ai/glossary/filter-sand) Filter sand is the special-grade sand inside a sand filter, and it wears out over years. [Flocculant](https://marinapool.multisites.ai/glossary/flocculant) A flocculant is a product that drops fine particles to the pool floor to be vacuumed out. [Flow switch](https://marinapool.multisites.ai/glossary/flow-switch) A flow switch is a sensor that confirms water is moving through a salt cell or heater. [Free chlorine](https://marinapool.multisites.ai/glossary/free-chlorine) Free chlorine is the chlorine in pool water that is still active and ready to kill germs and algae right now. [Free estimate](https://marinapool.multisites.ai/glossary/free-estimate) A free estimate is a price quote with no charge for the visit. [Freeze](https://marinapool.multisites.ai/glossary/freeze) A freeze is air temperature at or below 32 degrees Fahrenheit, the point where water turns to ice. [Freeze guard](https://marinapool.multisites.ai/glossary/freeze-guard) Freeze guard is a control that starts the pump when the air gets cold to keep water moving. [Freeze protection](https://marinapool.multisites.ai/glossary/freeze-protection) Freeze protection is a set of steps that keep water moving or drained so equipment does not freeze. [Freeze sensor](https://marinapool.multisites.ai/glossary/freeze-sensor) A freeze sensor is a sensor that reads air temperature for freeze protection. [Full-service plan](https://marinapool.multisites.ai/glossary/full-service-plan) A full-service plan is a pool care plan where the company handles both cleaning and chemicals. ## G [Gas heater](https://marinapool.multisites.ai/glossary/gas-heater) A gas heater burns natural gas or propane to heat pool water quickly. [GFCI](https://marinapool.multisites.ai/glossary/gfci) A GFCI is a ground fault circuit interrupter, an outlet or breaker that cuts power fast when it detects a shock hazard. [Green algae](https://marinapool.multisites.ai/glossary/green-algae) Green algae is the most common pool algae, and it turns water green and can bloom within days. [Green pool cleanup](https://marinapool.multisites.ai/glossary/green-pool-cleanup) A green pool cleanup is a one-time deep clean that turns algae-filled water back to clear. [Gunite](https://marinapool.multisites.ai/glossary/gunite) Gunite is concrete sprayed dry through a hose with water added at the nozzle, used to build many pool shells. ## H [Hail](https://marinapool.multisites.ai/glossary/hail) Hail is falling ice stones that can damage pool covers, lights, and equipment housings. [Hairline crack](https://marinapool.multisites.ai/glossary/hairline-crack) A hairline crack is a very thin crack in the surface finish that is often cosmetic. [Hard freeze](https://marinapool.multisites.ai/glossary/hard-freeze) A hard freeze is a longer, colder freeze that can crack pipes, pumps, filters, and heaters. [Hard water](https://marinapool.multisites.ai/glossary/hard-water) Hard water is water with high calcium and minerals that can leave scale. [Heat exchanger](https://marinapool.multisites.ai/glossary/heat-exchanger) The heat exchanger is the part of a heater that passes heat into the pool water. [Heat pump](https://marinapool.multisites.ai/glossary/heat-pump) A heat pump is an electric heater that moves heat from the air into the water. [Heat wave](https://marinapool.multisites.ai/glossary/heat-wave) A heat wave is several days of very high heat that raise chlorine use and water temperature. [Hot tub](https://marinapool.multisites.ai/glossary/hot-tub) A hot tub is a self-contained heated tub with its own heater, pump, and filter, built for soaking. ## I [Igniter](https://marinapool.multisites.ai/glossary/igniter) The igniter is the part that lights the gas burner in a heater. [Impeller](https://marinapool.multisites.ai/glossary/impeller) The impeller is the spinning part inside the pump that moves water. [Inline chlorinator](https://marinapool.multisites.ai/glossary/inline-chlorinator) An inline chlorinator is a feeder in the plumbing that dissolves chlorine tablets. [IPSSA](https://marinapool.multisites.ai/glossary/ipssa) IPSSA is the Independent Pool and Spa Service Association, a trade group for pool service pros. ## L [Lab water test](https://marinapool.multisites.ai/glossary/lab-water-test) A lab water test is a full water analysis from a pool store or a service company. [Langelier Saturation Index](https://marinapool.multisites.ai/glossary/langelier-saturation-index) The Langelier Saturation Index is a number that predicts whether pool water will scale or etch surfaces. [Leak detection](https://marinapool.multisites.ai/glossary/leak-detection) Leak detection is the work of finding where a pool or its plumbing loses water. [LED pool light](https://marinapool.multisites.ai/glossary/led-pool-light) An LED pool light is a low-energy underwater light that lasts a long time and can show many colors. [Liability insurance](https://marinapool.multisites.ai/glossary/liability-insurance) Liability insurance is coverage that pays for damage a contractor causes on a job. [Lid O-ring](https://marinapool.multisites.ai/glossary/lid-o-ring) The lid O-ring is the rubber ring that seals the pump lid and keeps air out. [Light niche](https://marinapool.multisites.ai/glossary/light-niche) A light niche is the housing set in the pool wall that holds the pool light and its cord. [Liquid chlorine](https://marinapool.multisites.ai/glossary/liquid-chlorine) Liquid chlorine is sodium hypochlorite in liquid form, and it adds chlorine without adding cyanuric acid. [Live oak debris](https://marinapool.multisites.ai/glossary/live-oak-debris) Live oak debris is the leaves and catkins that live oak trees drop and that load skimmers and filters. ## M [Main drain](https://marinapool.multisites.ai/glossary/main-drain) The main drain is the drain at the deepest point of the pool that pulls water down to the pump. [Metal stain](https://marinapool.multisites.ai/glossary/metal-stain) Metal stains are brown, green, or purple marks caused by iron, copper, or other metals in the water. [Mosquito breeding](https://marinapool.multisites.ai/glossary/mosquito-breeding) Mosquito breeding happens in standing water, including neglected pools, where mosquitoes lay eggs. [Motor bearings](https://marinapool.multisites.ai/glossary/motor-bearings) Motor bearings are parts that let the motor shaft spin, and worn ones make a screaming sound. [Multiport valve](https://marinapool.multisites.ai/glossary/multiport-valve) A multiport valve is a valve on a sand or DE filter that sets filter, backwash, rinse, and other modes. [Muriatic acid](https://marinapool.multisites.ai/glossary/muriatic-acid) Muriatic acid is a strong acid used to lower pH and total alkalinity. [Mustard algae](https://marinapool.multisites.ai/glossary/mustard-algae) Mustard algae is a yellow-brown algae that clings to shady walls and resists normal chlorine. ## O [One-time cleaning](https://marinapool.multisites.ai/glossary/one-time-cleaning) A one-time cleaning is a single pool clean with no weekly contract. [Oxidizer](https://marinapool.multisites.ai/glossary/oxidizer) An oxidizer is a chemical that breaks down organic waste in the water, and chlorine is one. ## P [Partial drain and refill](https://marinapool.multisites.ai/glossary/partial-drain-and-refill) A partial drain and refill replaces some of the pool water to lower cyanuric acid, calcium, or salt. [Parts and labor](https://marinapool.multisites.ai/glossary/parts-and-labor) Parts and labor are the two main charges on a repair bill: the items replaced and the time to do the work. [Pebble finish](https://marinapool.multisites.ai/glossary/pebble-finish) A pebble finish is a pool surface made of small natural stones mixed into cement. [pH](https://marinapool.multisites.ai/glossary/ph) pH is a scale that shows how acidic or basic water is, and it affects chlorine strength and swimmer comfort. [Phosphates](https://marinapool.multisites.ai/glossary/phosphates) Phosphates are a nutrient that can feed algae growth in pool water. [PHTA](https://marinapool.multisites.ai/glossary/phta) PHTA is the Pool and Hot Tub Alliance, a US trade group that sets industry standards. [Pink slime](https://marinapool.multisites.ai/glossary/pink-slime) Pink slime is a pink bacteria film often found in shaded spots, fittings, and low-flow areas. [Plaster](https://marinapool.multisites.ai/glossary/plaster) Plaster is a mix of white cement and marble dust used as the smooth interior finish of many concrete pools. [Pollen season](https://marinapool.multisites.ai/glossary/pollen-season) Pollen season is the spring and fall time when tree pollen coats pool water and clogs filters. [Pool alarm](https://marinapool.multisites.ai/glossary/pool-alarm) A pool alarm is a device that sounds when someone enters the water or a door to the pool opens. [Pool automation](https://marinapool.multisites.ai/glossary/pool-automation) Pool automation is a control system that runs the pump, lights, heater, and more from a panel or app. [Pool barrier](https://marinapool.multisites.ai/glossary/pool-barrier) A pool barrier is a fence or wall meant to keep children away from the water. [Pool closing](https://marinapool.multisites.ai/glossary/pool-closing) Pool closing is shutting a pool down for a season. Many North Texas owners keep their pools running instead. [Pool deck](https://marinapool.multisites.ai/glossary/pool-deck) The pool deck is the surface around the pool, often concrete, travertine, or pavers. [Pool filter](https://marinapool.multisites.ai/glossary/pool-filter) The pool filter is the equipment that traps dirt and fine particles from the water. [Pool heater](https://marinapool.multisites.ai/glossary/pool-heater) A pool heater is equipment that warms pool water, usually gas or a heat pump. [Pool inspection](https://marinapool.multisites.ai/glossary/pool-inspection) A pool inspection is a check of the equipment, surfaces, and safety features, often before a sale or repair. [Pool light](https://marinapool.multisites.ai/glossary/pool-light) A pool light is a waterproof fixture mounted in the pool wall that lights the water for night swimming and safety. [Pool mastic](https://marinapool.multisites.ai/glossary/pool-mastic) Pool mastic is the common name for the flexible sealant that fills the joint between pool coping and the deck. [Pool opening](https://marinapool.multisites.ai/glossary/pool-opening) Pool opening is restarting a pool after it was closed or sat idle for a season. [Pool plumbing](https://marinapool.multisites.ai/glossary/pool-plumbing) Pool plumbing is the network of pipes and fittings that carry water between the pool and the equipment. [Pool pump](https://marinapool.multisites.ai/glossary/pool-pump) The pool pump moves water through the filter, heater, and chlorine system, and back to the pool. [Pool technician](https://marinapool.multisites.ai/glossary/pool-technician) A pool technician is a trained person who services pools, tests the water, and repairs equipment. [Pool timer](https://marinapool.multisites.ai/glossary/pool-timer) A pool timer is a clock that turns the pump or other equipment on and off at set times. [Post-storm algae](https://marinapool.multisites.ai/glossary/post-storm-algae) Post-storm algae is an algae bloom that follows rain, when chlorine is diluted and nutrients are added. [Power center](https://marinapool.multisites.ai/glossary/power-center) The power center is the electrical box that powers and controls pool equipment. [Pressure gauge](https://marinapool.multisites.ai/glossary/pressure-gauge) The pressure gauge is a gauge on the filter that shows system pressure and signals when to clean. [Pressure switch](https://marinapool.multisites.ai/glossary/pressure-switch) A pressure switch is a safety part that tells the heater water is flowing. [Pressure test](https://marinapool.multisites.ai/glossary/pressure-test) A pressure test checks pool plumbing lines for leaks by filling them with pressure and watching for a drop. [Pressure-side cleaner](https://marinapool.multisites.ai/glossary/pressure-side-cleaner) A pressure-side cleaner is driven by a return line or a booster pump. [Priming](https://marinapool.multisites.ai/glossary/priming) Priming is filling the pump with water so it can start pulling. [Pump basket](https://marinapool.multisites.ai/glossary/pump-basket) The pump basket is a basket inside the pump that catches debris before it reaches the impeller. [Pump motor](https://marinapool.multisites.ai/glossary/pump-motor) The pump motor is the sealed electric motor that turns the impeller and drives water through the system. ## Q [Quartz finish](https://marinapool.multisites.ai/glossary/quartz-finish) A quartz finish is a pool surface of crushed quartz mixed into cement. ## R [RAIL license](https://marinapool.multisites.ai/glossary/rail-license) A RAIL license is the Texas Residential Appliance Installer License, which allows limited electrical work on residential appliances, including pool equipment. [Recreational water illness](https://marinapool.multisites.ai/glossary/recreational-water-illness) Recreational water illness is sickness caused by germs in pools, spas, and splash areas. [Resurfacing](https://marinapool.multisites.ai/glossary/resurfacing) Resurfacing is replacing the interior finish of a pool, such as plaster, pebble, or quartz. [Return jet](https://marinapool.multisites.ai/glossary/return-jet) A return jet is the fitting in the pool wall where filtered, treated water flows back into the pool. [Robotic cleaner](https://marinapool.multisites.ai/glossary/robotic-cleaner) A robotic cleaner is a self-contained cleaner with its own motor and filter bag. ## S [Safety cover](https://marinapool.multisites.ai/glossary/safety-cover) A safety cover is a strong, tight cover that blocks access to the pool when no one is swimming. [Salt cell](https://marinapool.multisites.ai/glossary/salt-cell) The salt cell holds the plates inside a salt chlorine generator that make chlorine, and it wears out over time. [Salt chlorine generator](https://marinapool.multisites.ai/glossary/salt-chlorine-generator) A salt chlorine generator turns dissolved salt into chlorine inside the pool plumbing. [Salt level](https://marinapool.multisites.ai/glossary/salt-level) Salt level is the parts per million of salt in a saltwater pool, and the cell maker sets the target. [Salt system conversion](https://marinapool.multisites.ai/glossary/salt-system-conversion) A salt system conversion changes a chlorine pool to run on a salt chlorine generator. [Sand filter](https://marinapool.multisites.ai/glossary/sand-filter) A sand filter uses sand as the filter media, and you clean it by backwashing. [Sanitizer](https://marinapool.multisites.ai/glossary/sanitizer) A sanitizer is a chemical that kills germs in pool water, and in most pools it is chlorine. [Scale](https://marinapool.multisites.ai/glossary/scale) Scale is hard white or gray calcium buildup on tile, surfaces, and equipment. [Service call](https://marinapool.multisites.ai/glossary/service-call) A service call is a visit to diagnose or fix a problem. [Service log](https://marinapool.multisites.ai/glossary/service-log) A service log is a record of tests, doses, and work done at each pool visit. [Service route](https://marinapool.multisites.ai/glossary/service-route) A service route is the set of pools a technician visits on a given day. [Shaft seal](https://marinapool.multisites.ai/glossary/shaft-seal) The shaft seal is a small seal that stops water from leaking along the motor shaft. [Shock](https://marinapool.multisites.ai/glossary/shock) Shock is a large one-time dose of chlorine or another oxidizer used to clear chloramines, bacteria, or algae. [Shotcrete](https://marinapool.multisites.ai/glossary/shotcrete) Shotcrete is concrete mixed wet with water first and then sprayed to build pool shells. [Single-speed pump](https://marinapool.multisites.ai/glossary/single-speed-pump) A single-speed pump runs at one fixed speed, and newer federal rules limit new sales. [Skimmer](https://marinapool.multisites.ai/glossary/skimmer) The skimmer is the opening in the pool wall that pulls surface water and debris into the system. [Skimmer basket](https://marinapool.multisites.ai/glossary/skimmer-basket) The skimmer basket is a basket in the skimmer that catches leaves and debris from the surface. [Soda ash](https://marinapool.multisites.ai/glossary/soda-ash) Soda ash is sodium carbonate, a pool product used to raise a low pH back into range. [Sodium bicarbonate](https://marinapool.multisites.ai/glossary/sodium-bicarbonate) Sodium bicarbonate is plain baking soda, and pool owners use it to raise low total alkalinity. [Sodium bisulfate](https://marinapool.multisites.ai/glossary/sodium-bisulfate) Sodium bisulfate is a dry acid used to lower pH and total alkalinity. [Spa](https://marinapool.multisites.ai/glossary/spa) A spa is a small heated pool for soaking, often joined to a larger pool. [Spa blower](https://marinapool.multisites.ai/glossary/spa-blower) A spa blower is a device that pushes air into spa jets to make bubbles. [Spa jets](https://marinapool.multisites.ai/glossary/spa-jets) Spa jets are nozzles that push water or air into a spa for massage. [Spillway](https://marinapool.multisites.ai/glossary/spillway) A spillway is a spot where water flows over an edge, such as from a spa into a pool. [Stabilizer](https://marinapool.multisites.ai/glossary/stabilizer) Stabilizer is another name for cyanuric acid, and it slows chlorine loss in sunlight. [Startup service](https://marinapool.multisites.ai/glossary/startup-service) A startup service is a visit to restart a pool and its equipment after a long idle period. [Storm runoff](https://marinapool.multisites.ai/glossary/storm-runoff) Storm runoff is rain that carries dirt, pollen, and nutrients into the pool. [Structural crack](https://marinapool.multisites.ai/glossary/structural-crack) A structural crack is a wider crack that may mean the shell is moving or leaking. [Suction entrapment](https://marinapool.multisites.ai/glossary/suction-entrapment) Suction entrapment is a hazard where strong suction at a drain traps a swimmer under water. [Suction-side cleaner](https://marinapool.multisites.ai/glossary/suction-side-cleaner) A suction-side cleaner is an automatic pool cleaner that runs off the pump's suction line through the skimmer. [Swim season](https://marinapool.multisites.ai/glossary/swim-season) Swim season is the months a pool gets used. In North Texas this often runs from spring to fall. ## T [Tanning ledge](https://marinapool.multisites.ai/glossary/tanning-ledge) A tanning ledge is a shallow shelf in the pool, often for lounging chairs or kids. [TDLR](https://marinapool.multisites.ai/glossary/tdlr) TDLR is the Texas Department of Licensing and Regulation, which licenses some pool-related electrical work. [Test strips](https://marinapool.multisites.ai/glossary/test-strips) Test strips are paper strips that change color to give a quick estimate of water chemistry. [Thermostat](https://marinapool.multisites.ai/glossary/thermostat) A thermostat is the control that sets and reads pool water temperature. [Total alkalinity](https://marinapool.multisites.ai/glossary/total-alkalinity) Total alkalinity is the water's ability to resist pH changes, and it works as a pH buffer. [Total chlorine](https://marinapool.multisites.ai/glossary/total-chlorine) Total chlorine is the sum of free chlorine and combined chlorine, as shown on a standard chlorine test. [Total dissolved solids](https://marinapool.multisites.ai/glossary/total-dissolved-solids) Total dissolved solids, or TDS, is the total of everything dissolved in the water. [Transformer](https://marinapool.multisites.ai/glossary/transformer) A pool light transformer is a device that lowers household voltage to a safer, lower voltage for some pool lights. [Trichlor](https://marinapool.multisites.ai/glossary/trichlor) Trichlor is a slow-dissolving chlorine tablet that also adds cyanuric acid and lowers pH. [Two-speed pump](https://marinapool.multisites.ai/glossary/two-speed-pump) A two-speed pump has a high speed and a low speed setting. ## U [Union fitting](https://marinapool.multisites.ai/glossary/union-fitting) A union fitting is a threaded joint in pool plumbing that you can unscrew so equipment can be removed for service. [UV exposure](https://marinapool.multisites.ai/glossary/uv-exposure) UV exposure is strong sunlight that breaks down chlorine quickly when the water has no stabilizer. ## V [Vacation service](https://marinapool.multisites.ai/glossary/vacation-service) Vacation service is routine pool care that keeps the water safe and clear while the owner is away. [Valve actuator](https://marinapool.multisites.ai/glossary/valve-actuator) A valve actuator is a small motor on a pool valve that lets an automation system turn the valve for you. [Variable-speed pump](https://marinapool.multisites.ai/glossary/variable-speed-pump) A variable-speed pump runs at adjustable speeds and uses much less power at low speeds. [Vinyl liner pool](https://marinapool.multisites.ai/glossary/vinyl-liner-pool) A vinyl liner pool is a pool with a sheet of vinyl stretched over a wall frame and a sand or concrete floor. ## W [Water balance](https://marinapool.multisites.ai/glossary/water-balance) Water balance is the right mix of pH, alkalinity, hardness, and stabilizer for safe, clear water. [Water feature](https://marinapool.multisites.ai/glossary/water-feature) A water feature is a waterfall, fountain, or scupper that moves water for looks and sound. [Water restrictions](https://marinapool.multisites.ai/glossary/water-restrictions) Water restrictions are city limits on outdoor water use that can affect filling and draining a pool. [Waterline tile](https://marinapool.multisites.ai/glossary/waterline-tile) Waterline tile is the band of tile at the water's edge that resists stains, oils, and scale. [Weekly pool service](https://marinapool.multisites.ai/glossary/weekly-pool-service) Weekly pool service is a routine visit that tests the water, balances chemicals, and cleans the pool. [Wind debris](https://marinapool.multisites.ai/glossary/wind-debris) Wind debris is the leaves, dust, and trash that strong winds blow into the pool. [Winterization](https://marinapool.multisites.ai/glossary/winterization) Winterization is the work of preparing a pool and its equipment so they survive freezing weather. ## Need a hand with your pool? Call or text and tell us what your pool needs. Estimates are free for qualifying services, and same-day estimates are possible when the schedule allows. [Call (817) 896-1120](tel:+1-817-896-1120)[Get a quote](https://marinapool.multisites.ai/contact) ![A pool technician working on an equipment pad](https://marinapool.multisites.ai/_astro/technician-equipment-pad.BW5xZMNY_Zum1K5.webp)