A sour chemical substance containing hydrogen with the ability to dissolve metals, neutralize alkaline materials and combine with bases to form salts. Acid is used to lower (decrease) pH and total alkalinity of swimming pool and spa water. Examples are muriatic acid (hydrochloric) and dry acid (sodium bisulfate).

The amount of acid required to bring high pH and total alkalinity down to their proper levels. Determined by the acid demand test.

A reagent test usually used in conjunction with a pH test to determine the amount of acid needed to lower pH and total alkalinity levels.

Precipitation having an unusually low pH value (4.5 or lower) caused by absorption of air polluted by sulfur dioxide, carbon dioxide and nitrous oxide.

A thermoplastic sheet formed into a mold to make a spa or related equipment. It is first heated and then vacuumed onto the mold.

A mechanical device that forces air through holes in the floor, bubbler ring or hydrotherapy jets in a spa

A brass or plastic, manually operated valve located at the top of a filter tank for relieving the pressure inside the filter and for removing the air inside the filter (called bleeding the filter). Sometimes called a pressure-relief valve.

Microscopic plant-like organisms that contain chlorophyll. Algae are nourished by carbon dioxide (CO2) and use sunlight to carry out photosynthesis. It is introduced by rain or wind and grows in colonies producing nuisance masses. Algae are not disease-causing, but can harbor bacteria, and it is slippery. There are 21,000 known species of algae. The most common pool types and black, blue-green, green and mustard (yellow or drawn). Pink or red-colored algae-like organisms exist but are bacteria and not algae. Maintaining proper sanitizer levels, shocking and super chlorination will help prevent its occurrence.

Also called algicide – A natural or synthetic chemical designed to kill, destroy or control algae.

Also called base – A Class of compounds which will react with an acid to give a salt. Alkali is the opposite of acid.

Also more commonly called total alkalinity. A measure of the pH-buffering capacity of water. Also called the water’s resistance to change in pH. Composed of the hydroxides, carbonates and bicarbonates in the water. One of the basic water tests necessary to determine water balance.

Any one of several aluminum compounds used in pools to form a gelatinous floc on sand filters or to coagulate and precipitate suspended particles in the water.

Introduced into the water by swimmers as waste (perspiration or urine) or by other means. Quickly forms foul-smelling, body- irritating chloramines – a disabled, less- effective form of chlorine. See chloramines or combined chlorine.

A chemical added to the water to make the suds or foam go away. These products do not remove the source of the sudsing. Most often, the water must be drained and refilled to remove the soaps, oils and other causes of foaming. Shocking and super chlorination may help prevent foaming.

A chemical compound used to remove iron stains from fiberglass and vinyl-liner pools.

A robot that travels through the swimming pool sucking up debris or a series of pop up heads that spray water causing debris to move toward bottom drain of the swimming pool.

An electric cover system for a swimming pool or spa. Generally the swimming pool needs to be a true rectangle for these systems. If the cover fits tightly over the swimming pool, spa or other body of water over 24 inches deep, a portion of the fence code requirements may be met. The cover is generally used for safety but there is also a significant solar heating and cleaning benefit.

A pool maintenance system that will agitate or vacuum debris from the pool interior automatically.

A term used or an index used to compare the oxidizing power of chorine-containing products to gas chlorine. It permits easy comparison of chlorine compounds.

The amount of chlorine, both free and combined in the pool water that is available to sanitize or disinfect the water. Sometimes called residual chlorine.

The backing up of water through a pipe in the direction opposite to normal flow.

The process of thoroughly cleaning the filter by reversing the flow of water through it with the dirt and rinse water going to waste.

 Single-celled microorganisms of various forms, some of which are undesirable or potentially disease-causing. Bacteria are controlled by chlorine, bromine or other sanitizing and disinfecting agents.

A chemical or element that kills, destroys, or controls bacteria.

Baking Soda: Chemically called sodium bicarbonate. It is white powder used to raise the total alkalinity of pool or spa water without having much effect on pH.

The correct ratio of mineral content and pH level that prevents the water from being corrosive or scale forming.

 A simple non-return valve consisting of a ball resting on a cylindrical seat within a liquid passageway.

Also called basic – A class of compounds which will react with an acid to give a salt. Base is the opposite of an acid. See alkali.

 This term usually refers to liquid chlorine (sodium hypochlorite 12% available chlorine). It is the same chemical used in laundry bleach but pool chlorine is 12% available chlorine while laundry bleach is about 5 to 6%% available chlorine.

An air pump used to push air into a spa through the jets or through holes in the seat.

A condition caused by too much copper in the pool water. Blue fingernails are not caused by chlorine. The copper may get into the water by the bad practice of placing trichlor tabs in the skimmer. This acidic product will cause low-pH water, which will in turn dissolve metals in the equipment. The dissolved metal (usually copper) then stains hair, fingernails and, eventually, pool walls. It can also be caused by keeping the pH too low or misusing acid.

The process of adding sufficient free available chlorine to completely oxidize all organic matter and ammonia or nitrogen compounds. All chlorine added after that point is free available chlorine.

By-products formed when bromine reacts with swimmer waste (perspiration or urine), nitrogen or fertilizer. Bromamines are active disinfectants and do not smell, although high levels are body irritants. Bromamines are removed by super chlorination or shock treating.

A common term for a bromide salt used to supply bromide ions to the water so they may be oxidized or changed into hypobromous acid, the killing form of bromine. Used as a disinfectant.

A mechanical or electrical device for dispensing bromine at a controlled rate. Most often a canister or floater filled with tablets of bromine.

A common name for a chemical compound containing bromine that is used as a disinfectant to destroy bacteria and algae in swimming pools and spas. Available as a tablet or as sodium bromide, a granular salt.

Abbreviation for British Thermal Unit. The amount of heat necessary to raise 1 lb. of water 1 degree Fahrenheit.

A substance or compound that stabilizes the pH value of a solution. It is also the water’s resistance to change in pH.

An arrangement of pipes, gates and valves by which the flow of water may be passed around a piece of equipment or diverted to another piece of equipment; a controlled diversion.

A compound of chlorine and calcium used as a disinfectant, sanitizer, bactericide, algaecide and oxidizer in swimming pool and spa water. It is available as a white granular material usually used for super chlorination or it is available as tablets used in a feeder for regular chlorination. It usually contains 65% available chlorine.

Crystalline compounds formed in swimming pool and spa water when the calcium, pH and total alkalinity levels are too high. Once formed, the crystals adhere to the plumbing, equipment, pool walls and bottom. These crystals are better known as scale.

A soluble white salt used to raise the calcium or total hardness level in the pool or spa.

The calcium content of the water. Calcium hardness is sometimes confused with the terms water hardness and total hardness. Too little calcium hardness and the water is corrosive. Too much calcium hardness and the water is scale forming. One of the basic water tests necessary to determine water balance. Minimum level is 150 ppm. Ideal range is 200 to 400 ppm.

In most states a consumer has three business days to cancel a home improvement contract if that contract is signed in the home of a buyer.

A replaceable porous element made of paper or polyester used as the filter medium in cartridge filters.

A pool or spa water filter that uses a replaceable porous element made of paper or polyester.

A water feature streaming out from a wall of raised bond beam or raised spa.

A pump consisting of an impeller fixed on a rotating shaft and enclosed in a casing or volute and having an inlet and a discharge connection. The rotating impeller creates pressure in the water by the velocity derived from the centrifugal force.

A mechanical device in a pipe that permits the flow of water or air in one direction only.

(Pronounced KEY-late) – also called sequester – It is the process of preventing metals in the water from combining with other components in water to form colored precipitates that stain the pool walls and bottom or produce colored water.

Copper algaecides that contain a special ingredient to prevent the copper from staining the pool walls and bottom or producing colored water.

Any of several types of devices that dispense chemicals into the pool or spa water at a predetermined rate. Some dispense chlorine or bromine while others dispense pH-adjusting chemicals.

A chemical used to make chlorine harmless. Used in test kits to counteract the bleach- ing effect of the chlorine or bromine in order to increase the accuracy of pool water tests. Sold as chlorine and bromine neutralizer, it is used to destroy excessive amounts of chlorine or bromine, so the high levels will not affect swimmers.

Undesirable, foul-smelling, body-irritating compounds formed when insufficient levels of free available chlorine react with ammonia and other nitrogen-containing compounds (swimmer and bather waste, fertilizer, perspiration, urine, etc.). Chloramines are still disinfectants, but they are a much weaker, ineffective form of chlorine. Chloramines are removed by super chlorination or shock treating.

A mechanical or electrical device for dispensing chlorine at a controlled rate. Most often a canister or floater filled with tablets of chlorine.

A term used to describe any type of chlorine compound used as a disinfectant in swimming pool and spa water or to kill, destroy or control bacteria and algae. In addition, chlorine oxidizes ammonia and nitrogen compounds (swimmer and bather waste).

The amount of chlorine necessary to oxidize all organic matter (bacteria, algae, chloramines, ammonia and nitrogen compounds) in the pool or spa water.

A chemical compound that when used in conjunction with chlorine makes the chlorine perform better as an algaecide.

An electrical device that generates chlorine from a salt solution in a tank or from salt added to the pool water.

This is a term that implies that an over- abundance of cyanuric acid (stabilizer or conditioner) in the water would cause the chlorine to be all “locked up.” This is not true.

The amount of chlorine left in the pool or spa water after the chlorine demand has been satisfied.

Also called coagulant or flocculant – A chemical compound used to gather (coagulate or agglomerate), or to precipitate suspend- ed particles so they may be removed by vacuuming or filtration. There are two types; inorganic salts of aluminum (alum) or water- soluble organic polyelectrolytes.

The degree of transparency of the water.

An organic polyelectrolyte used to gather (coagulate) suspended particles in the water.

Undesirable, foul-smelling, body-irritating compounds formed when insufficient levels of free available chlorine react with ammonia and other nitrogen-containing compounds (swimmer and bather waste, fertilizer, perspiration, urine, etc.). Combined chlorine is still a disinfectant, but it is a much weaker, ineffective form of chlorine.

A document signed by a contractor, supplier or subcontractor evidencing that the job has been paid in full, subject to the check for the services clearing the bank.

Chemically, conditioner is cyanuric acid. It slows down the degradation of chlorine in the water by sunlight. Minimum level is 10 ppm. Too much does not slow down chlorine activity or effectiveness. Conditioner does not protect bromine from sunlight.

Required by most states. In California a swimming pool contractor must post a $12,500.00 bond with the Contractors’ Board. This is a fund used to settle disputes that the contractor refuses to settle himself. A bond may be posted via an insurance policy or in cash. Generally a contractor that posts a cash bond is considered more financially sound than a contractor that posts a bond via insurance.

In California, as in most states, a valid contractor’s license is required to do business as a swimming pool contractor. In California the license required is C-53. A contractor without a C-53 license cannot build a swimming pool. This includes landscape contractors.

The finished edge of the swimming pool. Usually 12 inches wide.

It is one of nature’s elements. It is also used for various parts of equipment and plumbing in swimming pools and spas. Corrosive water caused by misuse of chemicals, improper water balance, or placing trichlor tablets in the skimmer can cause copper to be dissolved from the equipment or plumbing and deposit the precipitates on hair, finger- nails or pool walls. High levels of copper also cause green water. Copper is also used as an algaecide. Maximum level is about 0.2 ppm.

A chemical compound that contains the element copper. Copper sulfate was one of the original copper algaecides. Too much copper in the water can cause green-colored stains. Newer copper algaecides contain an ingredient that prevents the copper from staining but does not affect copper’s ability to kill algae. These special copper algaecides are called chelated copper algaecides.

The etching, pitting or eating away of the pool or spa or equipment. Caused by improper water balance, misuse of acid or acidic products or from soft water.

 A plumbing fitting that is used to connect two pieces of pipe.

A cover used on pools, spas and hot tubs that rests on the lip (coping) of the pool or spa deck – not a flotation cover. Used as a barrier to swimmers and bathers, and for maintenance and thermal protection.

A cover that, when placed on the water’s surface of a pool, spa or hot tub, increases the water temperature by absorption and transmission of solar radiation; reduces evaporation and prevents wine-borne debris from entering the water.

A cover that is secured around the perimeter of a pool, spa or hot tub that provides a barrier to bathers and debris when the pool, spa or hot tub is closed for the season.

Also called condition and stabilizer – Chemically, conditioner is cyanuric acid. It protects chlorine in the water from being destroyed by sunlight. Minimum level is 10 ppm. Too much does not slow down chlorine activity or effectiveness. Does not protect bromine from

Diatomaceous earth is a powder filtering agent made up of tiny sea diatoms. It attaches itself to the grids of a D.E. filter and filters out very small particles.

Diatomaceous Earth Filter – A filter designed to use diatomaceous earth (D.E.) as the filter medium. The D.E. is added through the skimmer with the pump on, which takes the D.E. and deposits it on a grid. The D.E. then becomes the filter medium.

In the swimming pool industry, decking is generally assumed to be concrete unless the term is proceeded with a different type. For example, brick decking or wood decking.

Those areas immediately adjacent to a pool, spa or hot tub that are specifically constructed or installed for use by bathers for sitting, standing or walking.

Also called anti-foam – A chemical added to the water to make the suds or foam go away. These products do not remove the source of the sudsing. Most often, the water must be drained and refilled to remove the soaps, oils and other causes of foaming. Shocking and super chlorination may help prevent foaming.

Also called D.E. – A white powder composed of fossilized skeletons of one-celled organisms called diatoms. The skeletons are porous and have microscopic spaces. The powder is added through the skimmer with the pump on and deposits itself on a grid. The powder then becomes the filter medium.

The common name for sodium dichlor. A fast-dissolving chlorine compound containing chlorine and cyanuric acid (stabilizer or conditioner). It has a neutral pH and is quick-dissolving, so it can be used for regular chlorination or super chlorination.

A porous plate, tube or other device through which air is forced and divided into minute bubbles for diffusion in the water. A diffuser can also be an over drain on a sand filter. A diffuser is also used on a closed- face impeller on a pump to concentrate water flow to the center of the impeller.

To kill al pathogenic (disease-causing) organisms.

Dissolve Solids: Also called TDS or total dissolved solids – A measure of the total amount of dissolved matter in water. Examples are calcium, magnesium, carbonates, bicarbonates, sodium, chlorides and metals. High levels can cause corrosion, colored water or salty taste. Maximum level is usually 2500 ppm for pools. Maximum level for spas is 1500 ppm over starting level.

A plumbing fitting used to change the direction or redirect the flow of water. Some diverter valves are used on pool/spa combinations to allow the use of the spa and then switch the flow back to the pool. A brand name diverter valve is called an Ortega valve, which is sometimes used to describe a diverter valve.

A recreational mechanism for entering a swimming pool, consisting of a semi-rigid board that derives its spring from a fulcrum mounted below the board and attached to the deck.

An indicator reagent used for the determination of free and total chlorine, bromine, ozone and other oxidizers in water. Better than using OTO for chlorine because it measures free chlorine.

This term usually refers to a plumbing fitting installed on the suction side of the pump in pools, spas and hot tubs. Sometimes called the main drain, it is located in the deepest part of the pool, spa or hot tub. It is not a drain, such as a drain on a kitchen sink. Main drains do not allow to drain to waste but rather connect to the pump for circulation and filtration.

Chemically, sodium bisulfate. A dry white crystal that produces acid when added to water. It is used for lowering pH and total alkalinity. Safer to handle than muriatic acid.

The electric service for a swimming pool or spa must originate from the property’s main electric panel or from a properly sized sub panel. Sometimes, and usually in older homes, the electric panel or service is not adequate to handle the load of the swimming pool or spa. In that case a new panel or service may be required. There may be an extra charge for this work. Be careful and ask questions.

Removal of the soil in order to create the depth of the swimming pool. Clients should not assume that by using this term that “all” excavation is included with the project. Removal of vegetation, obstacles with easy access, hauling or total hours allowed are examples of pitfalls inherent in misunderstanding of what is or is not included in a construction agreement.

Apparatus that cleans the swimming pool or spa water via a tank containing cleanable cartridges or grids coated with diatomaceous earth (D.E.)

A water feature in various forms but usually with a man-made appearance.

Swimming pool walls, all or part, engineered and built to stand on their own without the support of the surrounding soil. “O” edge swimming pools built on slopes are examples of this condition.

The gas required to run a natural gas or propane swimming pool or spa heater is required to come from the source of the gas, either the natural gas meter or propane tank. Gas stub outs on the wall of the house generally will not allow enough flow to properly operate a gas swimming pool or spa heater. An exception might be in new construction where the gas line running through the house is sized properly to support a swimming pool or spa heater.

Unless agreed upon otherwise, including grading for items not included in a swimming pool or spa construction agreement are not included. A good example of this is decking. Unless the decking is included in a swimming pool or spa construction agreement, the grading for the decking is not included. This may include hauling away extra dirt. It is a good idea to have the decking contractor on site some time during the excavation process to advise.

The application under air pressure of a dry mixture of sand and cement with water added at the nozzle.

During swimming pool and spa excavation and trenching, if hard ground or rock is encountered that cannot be removed by, or in a reasonable time frame, the tractor on site and a larger machine or blasting is required there may be an extra charge. This is the standard in the industry nationwide.

Natural gas or electric apparatus that heats water as it passes through it. A swimming pool or spa heater has no tank.

Home owners association approval may be required prior to constructing a swimming pool. Though they vary widely, most HOAs require only the initial swimming pool design for approval. This can take up to 30 days so application HOA approval should be submitted as early as possible. There may also be a fee. The fee is generally not the responsibility of the swimming pool contractor.

If during excavation and trenching for a swimming pool or spa yard irrigation or drainage is damaged, the cost of repair and reroute is generally the responsibility of the owner. Be careful and ask questions.

Periodically through the construction of your swimming pool, your contractor will call for an inspection of the work by the city. The inspector will visit the project within 24 to 48 hours from request. He or she will enter the site using the same access as the workers so the home owner may not know that an inspection has been completed. If the gate is lock or there are dogs the inspector may leave and need to be recalled and there may be a fee for the re-inspection. Generally the contractor pays re-inspection fees. However it is the owner’s responsibility to leave appropriate access.

Stone facing on a walls raised bond beam or at a swimming pool or spa water line installed on edge. This process usually requires more materials and labor than standard facing. Be careful and ask questions.

Not really a drain but rather a suction point generally connected to the skimmer. Main drains are required to split into a minimum of two suction points at least 36 inches apart. Note: Suction for water features etc. are also required to split to two points at least 36 inches apart.

The flexible compound installed between the concrete decking and the coping of a swimming pool or spa. It is an essential element of prohibiting water from making its way under the swimming pool decking, there by causing structural problems such as rising or settling of the concrete decking.

In most states, including California, if a subcontractor or supplier that delivers to, or supplies services to your property is not paid, he has the right to place a lien on the improved property to protect his right to be paid. This is the case even if a contractor is paid but he in turn does not pay his suppliers or subcontractors. Those suppliers and subcontractors still have lien rights. A subcontractor or supplier must file what is called a preliminary notice within 20 days of completion of his work in order to maintain his lien rights.

A water feature that gives the illusion that the swimming pool is flowing into the horizon.

An upgrade finish for the bottom of a swimming pool installed in a variety of colors and textures.

Most cities and counties prior to construction of a swimming pool or any other structure on the property require a plan check by their zoning, planning, engineering and building departments. The fee for this check and approval is generally paid by the contractor. In addition, the cities and counties require inspection/approval of the work periodically through the construction process.

The standard finish for the bottom and sides of a swimming pool usually in white but can be installed in gray, tan or black.

A pool designed with the water at the same level as the surrounding hardscape. This illusion is created by running the water into a full perimeter gutter, similar to a “0” edge pool. 

Top view layout of back yard including swimming pool drawn to scale. Some contractors use computer software that creates 3-D view or perspectives.

Swimming Pool Engineering: Structural design and calculations of swimming pool as per plan. Most cities or counties require an original signature by a certified engineer on each page of engineering and calculations. Most swimming pool contractors hire an outside engineer for this work.

Generally considered the pump(s), filter and heater (if ordered). Swimming pool equipment is generally located between 20 feet and 50 feet from the swimming pool of spa. It usually occupies a 3 ft. by 7 ft. rectangle and is about 4 ft. tall. There may be a set back from property lines or openable windows of the house.

Standard swimming pool lights are 500 watt incandescent. Upgrade lights are LED and can be in colors.

The placement of PVC (schedule 40 and 80 plastic) piping associated with the swimming pool, spa, and water feature circulation elements. There are many styles of plumbing for swimming pools, etc. and therefore very few building codes associated with swimming pool or spa plumbing. So there are virtually no inspections by cities or county required. Be careful and ask questions to guarantee the best and proper installation of plumbing.

The start-up phase of swimming pool or spa construction is the time when all pumps, filters, heaters and other mechanical apparatus requiring water in the swimming pool are turned on for the first time.

 In most states, including California, by law a subcontractor or supplier who delivers to or improves a property must file a preliminary notice of intent to lien with 20 days of completion of his work. Failure to do so voids his lien rights.

Draws water from the swimming pool and pushes it through the filter.

A raised wall of the swimming pool installed to retain a slope or as a cosmetic element to create elevation change in the swimming pool design. A raised bond beam is generally faced in tile or stone.

Inlets to the swimming pool allowing filtered water to enter the swimming pool. A loop system where the main return line circles the entire swimming pool with several branches emanating clean water under equal pressure is the best style of return system.

Required in most states to be part of any swimming swimming pool construction contract.

The application under pressure of wet mix of sand, pea gravel and cement delivered wet from concrete batch plant.

Sump with leaf basket at water’s edge. This is the main point of suction to the pump then on through the filter

The placement of reinforcing bar (rebar) within the swimming pool structure as per approved engineering furnished by the swimming pool contractor. Since most cities and counties do not do a site check prior to issuing a building permit, it is up to the swimming pool contractor to disclose the conditions of the site that might require “special” engineering. If these conditions are not disclosed and the building inspector fails the inspection, it is the owner’s responsibility to pay for the additional engineering and structure required to meet the site conditions. Be careful and ask questions.

Stone facing on walls raised bond beam or at swimming pool or spa water line installed flat with grout joints separating each piece.

Pressure on the soil near the swimming pool that requires the swimming pool structure to be stronger. Surcharge occurs at a 45 degree angle downward into the soil at the bottom of the surcharge item’s closest point to the swimming pool. Swimming pools close to a house, patio cover post, slope or large boulders are constructed with engineering that addresses surcharge. The pool itself can also create surcharge if constructed on the high side of a retaining wall. In this condition either the retaining wall has to engineered and built to support the pool or the swimming pool has to be constructed in a freestanding manor so that surcharge begins at the base of the swimming pool structure and on a 45 degree angle misses the bottom of the retaining wall.

A document signed by contractor, supplier or subcontractor evidencing that the job has been paid in full.

If during excavation and trenching for a swimming pool or spa house utilities lines or sprinklers are damaged, the cost of repair and reroute is generally the responsibility of the owner. Be careful and ask questions.
water feature in various forms but usually made of stone or boulders.

The ceramic, porcelain or stone material used to cover the top vertical six inches of the swimming pool structure. The waterline of the swimming pool generally sits about half way up on the waterline tile.