AIR-RELIEF VALVE: This also known as a pressure-relief valve.  It is a manually-operated brass or plastic valve located at the top of the filter tank for releasing the pressure inside the filter and eliminating the air inside the filter (draining the filter)

ALGAE:  Over 20,000 species known to exist.  Algae may form on your pool surfaces.  We mainly see algae to be known as green algae but it may also be yellow (mustard algae), black, blue-green, or any color in between. It may form separate spots or seem to grow in sheets.  Algae are living breathing organisms that need warmth, sunlight, and CO² to thrive Microscopic plant-like organisms that contain chlorophyll. nourished by carbon dioxide (CO2) and use sunlight to carry out photosynthesis. It can be introduced by rain or wind and grows in colonies, producing nuisance masses. Algae can harbor bacteria and can be slippery. There are thousands of known species of algae. The most common types of algae found in pools are black, blue-green, green and mustard (yellow or drawn). Pink algae are not algae at all but a form of bacteria.

ALGAECIDES: Chemical compounds intended to eradicate, prevent and control algae.

BACKFLOW: an unwanted flow of water going in the opposite direction

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

BALANCERS: Chemical compounds designed to prevent corrosion and staining by balancing the pH, total alkalinity and calcium hardness in swimming pool water.

BROMIDE: Used as a disinfectant.

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

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

CHECK VALVE: A valve installed your circulation system to keep water from flowing backwards in the system when the pump is turned off.

CHEMICAL FEEDER: A device that dispenses chemicals into pool, spa or hot tub water at a predetermined rate. Some dispense chlorine or bromine while others dispense pH-adjusting chemicals.

CHLORINE NEUTRALIZER: A chemical used to make chlorine harmless. It is used in test kits to counteract the bleaching 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.

 CHLORINE: A disinfectant used in swimming pool and hot tubs to kill, destroy or control bacteria and algae. In addition, chlorine oxidizes ammonia and nitrogen compounds.

COPING aka EDGING:  The cap or top lip on the pool, spa or hot tub wall that provides a finished edge around the pool or spa. It can be formed, cast in place or precast, or prefabricated of extruded aluminum or rigid vinyl. It may also be part of the system that secures a vinyl liner to the top of the pool wall.

CORROSION: The gradual deterioration of matter such as a pool or hot tub or equipment. Can be caused by improper water balance, misuse of acid or acidic products or from soft water.

D.E.: Diatomaceous Earth — a porous substance used in certain types of pool filters.

DIVERTER VALVE: A fitting used to change the direction of 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.

 DRAIN aka MAIN DRAIN: This term usually refers to a pool plumbing fitting installed on the suction side of the pump in pools, spas and hot tubs. The drain is located at the deepest part of the pool, spa or hot tub. Pool main drains do not allow the water to drain to waste but rather connect to the pump for circulation and filtration.

 FIBERGLASS: Fiberglass is a strong lightweight material and is used for many products. Although it is not as strong and stiff as composites based on carbon fiber, it is less brittle, and its raw materials are much cheaper. Its bulk strength and weight are also better than many metals, and it can be more readily molded into complex shapes.

FILTRATION RATE: The rate at which the water is traveling through the filter, expressed in U.S. gallons per minute (gpm) per square foot of filter area.

 GPM: “gallons per minute.”

GUNITE: A mixture of cement and sand sprayed with a high-pressure gun onto contoured and supported surfaces to build a pool. Gunite is mixed and pumped to the site dry, and water is added at the point of application. Plaster is usually applied over the Gunite.

NEUTRALIZER: a chemical compound used to reduce or completely remove the chlorine content in water.

OXIDIZER: A non-chlorine shocking mixture that removes or destroys built-up contaminants and chloramines in pool water without raising chlorine levels.

POOL COVER, (HARD-TOP): A cover used on pools, spas and hot tubs that rests on the lip (coping) of the pool or hot tub deck; this is not a flotation cover. Used as a barrier to swimmers and bathers and for maintenance and thermal protection, this will also help prevent damage from the cold winter months.

POOL FILTER aka FILTER:  Pool filters remove dirt and debris by passing water through a bed of sand, cartridge or D.E. (diatomaceous earth).

PUMP: A device usually ran on an electric motor, which causes hydraulic flow and pressure for the purpose of filtration, heating and circulation of pool and hot tub water. Typically, a centrifugal pump is used for pools, spas and hot tubs.

PUMP CAPACITY: The amount of liquid a pump is capable of moving during a specified period of time. This is usually listed in gallons per minute or gpm.

pH: Abbreviation for Potential Hydrogen. This indicates the level of acidity or alkalinity of water on a scale ranging from 0-15. A low pH can cause the plaster to be etched, as well as metal corrosion and eye irritation. A high pH can cause scale formation, chlorine inefficiency and eye irritation. The ideal range for pH in swimming pools is typically 7.4 to 7.6.

SANITIZERS: Compounds designed to destroy bacteria, algae and other living organisms. Sanitizers can also protect water from the effects of the sun.

SHOCK TREATMENT: The practice of adding significant amounts of an oxidizing chemical — (usually non-chlorine oxidizers, such as sodium persulfate or potassium peroxymonosulfate) — to the water to destroy ammonia and nitrogen compounds there are many reasons this is cause mainly, the environment and/or weather.

SKIMMER: An apparatus installed through the wall of a pool or hot tub that is connected to the suction line of the pump that draws water and floating debris in the water flow from the surface without causing much flow restriction.

SKIMMER BASKET: A removable, slotted basket or strainer placed in the skimmer on the suction side of the pump, which is designed to trap floating bits in the water flow from the surface without causing flow restriction.

TEST KIT: An apparatus or device used to monitor specific chemical residuals, levels, constituents or demands in pool or hot tub water. The most common pool and hot tub water tests are: pH, total alkalinity, free available chlorine, water hardness, cyan uric acid, iron and copper.

TURBIDITY: The cloudy or hazy condition of the water due to the presence of extremely fine particles in suspension that cannot be trapped by the filter because they are too small. Adding a clarifier, such as an organic polymer or alum, will coagulate the particles and make the filter more efficient.

VALUATION: The process of estimating what something is worth. Similar models determine the value based on the observation of market prices.

VINYL LINER aka Liner: It is one of many types of interior pool finishes. The liner is draped over a sand or cementitious floor, and locked into the top of the pools wall.