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Pool Care Glossary

Acid Demand: A titration test used to determine proper amounts of acid (or pH reducer) to reach correct levels. For example, to lower pH from 8.0 to 7.6, your pool may “demand” 2 qts of acid.

Algae: Microscopic organisms that capture light energy through photosynthesis with the help of the photosynthetic pigment chlorophyll. They appear either green, blue-green, black, brown or yellow. Nourished by sunlight and typically introduced by rain or wind, algae form colonies to create large masses in your swimming pool or spa. Algae in pools and ponds can cause the water to become cloudy, and in some cases can form a scum over the surface that blocks the sunlight from the water.

Algaecide: Substance used for killing and preventing the growth of algae. When used in a swimming pool, it allows you to use less chlorine for water purification, resulting in water that is more pleasant to swim in, without the stinging eyes and nose that too much chlorine can cause. Regular use of algaecide also prolongs the life of your water filtration systems, as there is less plant material to clog the filters and intakes of your pump. Product suggestions: Ultimate Algaecide, Concentrated Algaecide.

Algaestat: An algaecide kills algae, while an algaestat retards and prevents its genesis and growth in your pool.

Alkalinity: The amount of bicarbonate, carbonate, or hydroxide compounds in water. It acts a buffer against changes in your swimming pool’s water balance, namely pH, and is defined as the ability of the water to resist changes in pH. Low alkalinity is controlled by the addition of a base, and high levels of alkalinity are lowered by the addition of an acid. Product suggestions for control; Alkalinity increaser available in 5, 10 and 25 lb. pails.

Aluminum Sulfate: Product used as a flocculent which attracts suspended particles in the water together (green or cloudy pools). A small amount of this can also be used as an additive to your pool’s sand filter.

Automatic Pool Cleaner: A device which agitates or vacuums debris from the walls and floor of the pool.

Suction-Side Cleaners:
These cleaners attach with a hose to the pool’s main circulation system, typically through the skimmer, and they use the pool pump’s power to suck up debris. Some suction-side cleaners have brushes that loosen debris as the unit glides or jiggles along the pool’s floor and walls. Product suggestions: Dirt Devil Above Ground Cleaner, Barracuda In Ground Cleaner G4.
Pressure-Side Cleaners:
These cleaners also use a hose to attach to the pool’s main circulation system, but they are connected to the pool’s return line. They utilize the pressure created by the pool’s pump to push debris into an attached collection bag which is then periodically emptied. These have the advantage of lessening the overall wear on your pool’s filter system.
Booster Cleaners:
These cleaners utilize the same technology as pressure-side cleaners, however they require an independent pump to operate. This adds cost but provides the advantage of not using and thus taxing the pool’s main pump.
Robotic Cleaners:
These cleaners are propelled by multiple on-board motors with separate functions. Typically one motor propels the cleaner back and forth while another draws pool water in, thereby creating a vacuum that keeps the cleaner on the wall when climbing. A sensor tells the unit when it has reached the top of the wall so that it reverses direction and continues to clean until it comes out of the water again. Brushes on wide rollers rotate throughout the cleaning cycle, and debris is filtered out and collected in an on-board bag. Product  suggestions: In Ground Aquabot, In Ground Dolphin 2002 Automatic Cleaner.

Backwashing: The process of cleaning the medium and debris in a pool filter by the reverse flow of water through the filter. The backwash cycle is the time it takes to filter these contents.

Backwash Hose: The hose that attaches to the pool filter and empties backwash into a disposal area.

Bacteria: Germs that can get into your pool or spa by way of users and from the environment.

Bactericide: A product that kills bacteria. For example, Chlorine is a bactericide and germicide. Silver “algaecides” are actually more bactericide, and are useful on pink “algae.”

Balanced Water: The correct ratio of mineral content and pH that prevents water from becoming corrosive or scale forming.

Booster Pump: Secondary to the filter pump, a booster pump is used to power a pressure-side automatic pool cleaner.

Breakpoint Chlorination: When you shock your pool, the goal is to reach a high enough level of free chlorine, (measured in ppm), to break apart the combined chlorine molecules. With sufficient additions of chlorine, the breakpoint is reached and everything in the pool is oxidized.

Broadcast: Widely spreading chemicals in powder form over a pool or spa’s surface.

Bromine: A powerful and effective chemical sanitizer that is apart of a compound used to disinfect pool and spa water. It is often used as an alternative to chlorine, especially in hot tubs, spas, and indoor pools. It tends to be less harsh on skin, eyes, hair and swimwear, while also producing no chlorine-like odor. Due to its slow-dissolving nature, when Bromine is used in a pool, it must be dispensed by an automatic feeder. Available in 10, 25, 50 and 100 lb segments.

BTU (British Thermal Unit): A unit of measurement for the rate of gas usage by an appliance. Pool heaters, which typically burn either Propane or Natural Gas, are rated by their consumption.

Buffer: A base such as Sodium Bicarbonate (Baking Soda) that when added to your pool will increase alkalinity. In doing so the buffering capacity of the pool, (your pool’s resistance to pH change), is increased.

Buffering Capacity: The ability of a pool to resist changes in pH levels which is determined by the alkalinity, a close cousin to pH. A good buffering capacity helps maintain Balanced Water (See Above). If your pH bounces, or resumes previous levels soon after adjustment, your buffering capacity is too low and you need to check your total alkalinity.

Calcium Carbonate: Also known as scale, these crystalline deposits form on your pool surfaces, equipment, or even line your pipes. Eventually its buildup may clog or severely hinder the operation of your pool system. Properly balanced water can prevent this.

Calcium Chloride: A soluble white salt used to raise the calcium hardness of a pool. (See Hardness for more information).

Cartridge Filter: A surface-type filter component with fixed dimensions that is designed to remove suspended particles from water flowing through the filter. Cartridge filters are the typical choice for most spas and smaller above ground pools because they frequently must be removed from the tank and hosed thoroughly to remove dirt and debris. Large cartridge filters can operate for 6 months between cleanings, others however may require more frequent service. In general, cartridges should be replaced every 2-5 yrs, depending on the amount of debris it must filter.

Chloramine: A chlorine cell which has “died” due to its combination with a contaminant (such as ammonia or nitrogen) so that it is now useless for maintaining your pool. It emits a strong chlorine odor, which is not a sign of too much chlorine in the water, rather, too little available for sanitizing.

Chlorinator/Brominator: An automatic device used to deliver chlorine or bromine to pool water at a controlled rate, thus eliminating the need to manually add granular or liquid chlorine/bromine to maintain your swimming pool. See also Chlorine/Bromine Feeder. Product suggestions: Above-Ground In-Line Chlorinator, Floating Dearby Duck Chlorinator, Large Chlorinator.

Chlorine: A chemical that is apart of a compound that is used to disinfect swimming pool water.

Chlorine/Bromine Feeder: An automatic device used to deliver chlorine or bromine to pool water at a controlled rate, thus eliminating the need to manually add granular or liquid chlorine/bromine to maintain your swimming pool. Product suggestions: Above-Ground In-Line Chlorinator, Floating Derby Duck Chlorinator, Large Chlorinator.

Chlorine Demand: The chlorine required to eliminate contaminants in your pool. Chlorine may need to be added in large quantities before chlorine demand is satisfied.

Chlorine Generator: A device that acts as a miniature chlorine factory by creating its own sanitizer for your pool. Product suggestions: Aqua-Rite Chlorine Generator, Chlorease Saltwater Generator, LM Chlorine Generator.

Chlorine Residual: The amount of free chlorine in your pool.

Circulation Equipment: Anything associated with circulating pool water: pumps, hair and lint strainers, filters, valves, gauges, meters, heaters, surface skimmers, inlet/outlet fittings and feeders.

Circulation System: The connections of circulation equipment so that they perform as one to clarify, heat, and/or purify pool and spa water.

Clarifier (Floc): A non-ionic polymer flocculent that causes particles/solids in pools and spas to mass together, thus creating larger particles for easier removal through your filtration system. Product suggestion: Super Floc.

Combined Chlorine: Chlorine that has combined with nitrogen and ammonia, better known as chloramines. (See Chloramine for more information)

Coping: A clip (about two feet long) that fastens over the top of a pool wall to secure a vinyl liner into place. Product suggestion: Liner Coping Strips.

Corrosion: The pitting, etching, or eating away of material (usually metal) by a chemical action.

Cove: The area at which a pool wall and pool floor meet. Product suggestion: Peel & Stick Pool Cove.

Covers: An overlay above a pool, spa or hot tub.

Hard-top Covers:
A cover that rests on the lip of a spa or hot tub deck. They are used to prevent access or maintain temperature. Product suggestion: Thermal Guard Premium Spa Cover.
Safety Pool Covers:
A barrier for swimming pools that greatly reduces the risk of drowning by prevent access to the pool. It also prevents hazardous debris from entering the pool. Product suggestions: Arctic Armor Gold 15 year Mesh, Arctic Armor Gold 15 year Solid.
Solar Pool Covers:
A cover placed directly on a pool’s surface that helps increase the water temperature through solar heat conduction. A solar pool cover will also trap your pool’s heat in and reduce evaporation by around 95%, thereby helping you save up to 50% on pool chemical usage. Product suggestions: Above Ground 12 Mil Magni-Clear, In Ground 14 Mil Magni-Clear.
Winter Pool Covers:
A weather resistant pool cover that is secured around the perimeter of a pool or spa that serves as a barrier to debris during the closed season. Product suggestions: Above Ground Arctic Armor 15 yr Gold Winter Cover, In Ground Arctic Armor 15 yr Gold Winter Cover.

Cyanuric acid: A chemical compound that protects chlorine from loss due to sunlight. This is commonly referred to as Stabilizer. Available in 2, 4, and 7 lb. pails.

Deep Areas: Water depths of 5 feet or more.

Diatomite: The all-natural filter medium, made of powdered microscopic fossil skeletons and plankton, found in diatomaceous earth (DE) filters. Available in 25 lb bags.

DiChlor: Stabilized granular chlorine with 56% available chlorine and pH of 6 used as an easy way to add chlorine to outdoor pools where the stabilizer resists the chlorine loss caused by sunlight. Available in 10, 25, 50 and 100 lb. divisions.

Disinfectant: Chemicals that kill undesirable (pathogenic) organisms. Examples are chlorine, bromine, ionizers and copper/silver algaecides.

Diverter Valve: Used in a twin port skimmer, a diverter allows the operator to manipulate the amount of flow from the main drain and skimmer to the pump.

DPD Test: This is a testing method for measuring the amount of bromine, free chlorine and total chlorine.

Dry Acid: A granular product which lowers pH and total alkalinity of pool war which is also referred to as Sodium Biosulfate.

Effective Filter Area (EFA): Total surface area through which water flow rate will be maintained during filtration. EFA is different for the various types of filters:

EFA is the cartridge area that is exposed to the direct flow of water.
Diatomaceous Earth (DE):
EFA is the area of the septum. Available in 25 lb bags.
EFA is the filter surface that is perpendicular to the flow direction.
EFA is the area of the sand within the filter.

Efficacy: The power to produce an effect. Chlorine’s efficacy is affected by many factors, including the sun, water balance and the pool water’s chlorine demand.

Effluent: The output stream exiting the pool system, filter or other device.

Enzymes: Used in swimming pool formulations designed to break down and digest oils in a pool or spa.

Feeder: Mechanism that applies chemicals to swimming pools and spas (See Chlorinator/Brominator and Chlorine/Bromine Feeder). Product suggestions: Above-Ground In-Line Chlorinator, Floating Derby Duck Chlorinator, Large Chlorinator.

Fill Water: Used when filling or adding to the pool or spa’s water level. Whether from the hose or from a well, your fill water adds a different chemical make up and water balance (or lack thereof).

Filter: A device that removes solid particles and debris from pool water by circulating water through a porous substance or surface.

Cartridge Filter:
Uses a porous element and is disposable.
Diatomaceous Earth Filter:
Utilizes a thin layer of diatomaceous earth as its filter medium that periodically must be replaced.
Permanent-medium Filter:
Uses a permanent substance like sand that under normal circumstances, will not have to be replaced.
Vacuum Filter:
Uses suction from a pump to filter through a vacuum.

Filter Agitation: A mechanical or manual movement to dislodge the filter dirt and aid from the filter element.

Filter Cycle: The time it takes a filter to clean or backwash the pool water.

Filter Element: A device within a filter that traps solids and conducts water back to the pool or spa. An element usually includes laterals, a septum, septum support, or a cartridge.

Filter Medium: Finely graded material that removes particles from the water. Variations include sand, DE, or polyester fabric.

Filter Pump: The device that pulls water from the pool and pushes it through the filter on its way back to the pool. Product suggestions: Sta-Rite Pump, Hayward Super Pump.

Fingers: Thin flexible tubes that are placed vertically on a DE filter grid. They are coated with a thin “sock”, and then with DE medium.

Foaming: A term used to describe surface foam on your water, especially in spas/hot tubs. Foaming is caused by high TDS levels working in combination with soft water and oils. Use enzymes for foam control. Note: Certain low grade algaecides can foam when added to your pool or spa.

Free Chlorine: The portion of chlorine that is actually available to kill bacteria in the pool. This does not include chloramines or chlorine used up by the sun’s rays.

Ground-Fault Circuit-Interrupter (GFCI): A device that protects a circuit from branching off by quickly de-energizing the path of electricity when it senses current loss. These are required when operating a  robotic Automatic Cleaner.

Gunite: A can of cement or sand that, when mixed with water at the nozzle, is sprayed onto surfaces as a protective barrier to help build or re-do a pool or spa.

Handrail: Rails used to aid in entering or exiting a pool or spa. Variations include existence in or out of the pool, or as a part of the stairs.

Hardness (Calcium): Total hardness in the context of pool water refers to the total mineral content dissolved in the water. This is made up of calcium, magnesium, iron, manganese and other elements. The ideal range for calcium hardness is 250-350 ppm. If the calcium hardness is too low, the water becomes corrosive and results in the degeneration of pool equipment such as pumps, filters, and heaters. To combat this corrosion, calcium chloride should be used. On the other hand, if the calcium hardness is too high, the result will be scale formation on all pool surfaces resulting in clogged filters and pipes; reducing water flow and filtration efficiency. Signs to watch for are the pool water becomes cloudy and swimmers will complain of eye irritations. Product suggestions: Hardness Increaser in 4, 8 and 25 lb. pails.

Heater: A device used to heat the water of a pool or spa. How does each one work?

Direct Heater:
Heats the tubes through which water circulates.
Electric Heaters:
Elements submerged in water use electrical energy to extract heat from the air, upgrade it with a compressor, and then transfer it into the water. Product suggestions: Above Ground Pro 600 Heat Pump, In Ground Air Energy AE2000 Heat Pump.
Fossil-Fueled Heaters:
Natural or Propane gas is burned in a combustion chamber whereby the heat is then transferred into the pool water. Product suggestions: In Ground EnergyRite 2,
Raypak® HP Pool Heater.
Indirect Heaters:
Circulate steam or hot water inside an exchanger through which water flows.
Solar Heaters:
Transfer energy derived from the sun’s rays to heat the water as it passes through the solar panels. Solar heaters are available for both in ground and above ground systems!

Heat exchanger: An indirect heater that transfers heat (through a solid) from one fluid to another without mixing the two fluids which is the main heating feature in a pool heater.

Heat Pump: A direct heater in which a fan pulls warm outside air past Freon gas, transferring the latent heat in the outside air to the Freon gas that is being pumped through a condenser coil. The heat is then released to the water in the pool as it passes by the Freon gas in the evaporator coil. This process’s efficiency depends upon the amount of latent heat in the outside air and the relative humidity. The cooler the outside air and the lower the humidity, the less effective the unit is in heating the swimming pool. Product suggestions: Above Ground Pro 600 Heat Pump, In Ground Air Energy AE2000 Heat Pump

Hot Tub: A spa constructed of wood.

Hydrochloric Acid: A strong acid used to regulate the basicity (pH) of pools and spas.

Hydrotherapy Jets: Blends air and water to create high-velocity, turbulent streams of air enriched water.

Hypobromous Acid: A primary chemical compound responsible for sanitation in pools and spas treated with products based on chlorine or bromine.

Impeller: Rotating vanes of a pump which increase the flow of water.

Influent: The inflow of entering water to a pool filter or other device. Also called suction piping because it sucks water out of a pool or spa.

Iodine: An element related to chlorine and bromine used as a disinfectant. When used, chlorine is normally employed to free the elemental iodine.

Ionization: The process of using a low voltage current to disperse positively charged metal ions into the water. Since bacteria are negatively charged, these particles are attracted to the ions and are killed off as the charge penetrates the cell walls. The destroyed microorganisms clump together and are easily removed by a pool filter. Small amounts of chlorine are still needed with this method, but at levels typically 80% less than conventional pool systems.

Ionizer: An electric device mounted on your return line which delivers charged metal ions to the water flowing through it. Manufacturers may use either a copper anode and/or silver. Copper is an algaecide and algaestat, while silver is known for its properties as a bactericide. This limited technology has been replaced by the Vision System.

Ladder: A device used to enter or exit a pool.

Straddles a pool wall in an above-ground pool only. It has a safety feature that allows one side to lift and prevent access into the pool. Product suggestions: Neptune Stair Entry System w/Gate, Rotate & Lock A-Frame Pool Ladder.
This “candy cane” shaped ladder goes from deck to pool bottom. It can be used in in-ground pools or above-ground pools with decks. Product suggestions: Premium In-Pool Ladder, In-Ground Pool Ladder.

Laterals: Devices at the bottom of a filter that collect the filtered water and carry it up the tank to and back into the pool.

Liquid Acid: A liquid chemical (muriatic or hydrochloric acid) used to reduce pH and total alkalinity. This is a dangerous, corrosive chemical that should be handled with care.

Lithium Shock: Done with an expensive, white granular form of chlorine that has pH of 9 and available chlorine of 35%.

Liner (Vinyl): The vinyl membrane that acts as the container to hold the water in a pool.

These pool liners hang over the pool wall and are held in place with a liner clip. Product suggestions: Blue Swirl 20-Gauge Overlap, Solid Blue 20-Gauge Overlap Expandable.
These pool liners have a beaded top which snaps into a bead receiver located at the top of your pool wall just underneath the seat ledge. Product suggestion: Boulder Swirl Beaded,
Blue Diamond 25-gauge Beaded.
J-Hook (Uni-Bead):
These pool liners have a J-shaped piece that forms a grove (pocket) on top of the liner that hooks onto the pool wall corrugation. These liners are also very versatile because use of the hook is optional if the liner needs to be overlapped beyond the pool edge for a proper fit. Product suggestions: 25-gauge Rolling Rock J-Hook, 25-gauge Classic J-Hook.

Make-up Water: Fresh water used to fill or refill the pool.

Multiple Filter-Control Valve: A multi-port valve having at least 4 control positions for various filter operations. This combines the function of two or more single direct flow valves into one unit.

Muriatic Acid: The commercial name for hydrochloric acid. (See Hydrochloric Acid) For a safer alternative, try Blue Wave’s pH reducer available in 6, 15 and 30 lb buckets.

Non-Chlorine Shock: A granular form of potassium permonosulfate is added to your pool or spa to oxidize materials such as microorganisms, contaminants or chloramines. Advantages are that it does not require excessive chlorine use and allows swimming almost immediately after application, it does not harm liners, and does not upset water balance. Available in 6, 12 and 24 lb divisions.

Organic Matter: Perspiration, urine, saliva, suntan oil, cosmetics, lotions, dead skin and similar debris.

ORP (Oxidation Reduction Potential): A measure of the oxidizing agents in water which serves as a relative measure of the desired “work value” of a pool sanitizer.

OTO (Orthotolidine): A reagent which reacts with chlorine and bromine to produce specific colors on a test strip which measure the amount of chlorine or bromine in water.

Permanent Pool: A pool that cannot be readily disassembled.

Above-Ground Pool:
Removable pool on the ground that is between 36 and 54 inches deep. Product suggestions: San Marino 15′ Round 54″ Stainless Steel with 9″ Toprail, Bella 15′ Round 52″ Steel Pool with 8″ Toprail, Alta 15′ Round 48″ Steel Pool with 6″ Toprail.
On-Ground Residential Pool:
Removable pool that is on the ground and also has an excavated area below the earth.
In-Ground Pool:
Pool where sides rest in part or fully within the earth.
2-3 foot deep pool.
Wading Pool:
Pool that has shallow depth for wading.

pH: A measurement of water acidity or alkalinity (indicated by the hydrogen ion concentration) using a scale of 0 to 14. 0 is most acidic, 7 is neutral, and 14 is most basic. A swimming pool should have a pH of 7.2-7.6. This is best controlled with pH increaser available in 5, 10 and 25 lb buckets and pH reducer available in 6, 15 and 30 lb buckets.

Phenol Red: A pH indicator that causes the color of a solution to change depending on the pH balance.

Plaster: A mixture of cement and aggregate used as an interior finish on concrete pools or spas.

Pool Shock: The unstabilized chlorine made up of about 65% chlorine (with a ph of around 11) used to break down water-soluble organic matter. Product suggestions: Blast Out, Blitz, Burst.

ppm (Parts Per Million): The standard measure of total dissolved in one million parts of water.

Pre-Coat: The coating of filter aid on the septum of a DE filter at the beginning of each filter cycle.

Pressure Side: The section from the pump impeller towards the pool (also referred to as the return side of the plumbing).

Pressure Switch: A switch used in pool heaters which opens when the flow rate is insufficient for safe heater operation. This disrupts the circuit in the heater, preventing it from firing.

Public Pools: Pools that are operated by an owner, lessee, operator, or anyone else, regardless if there is a fee for use.

Class A:
Intended for competitive aquatic events.
Class B:
Intended for public recreational use.
Class C:
Operated by hotels, motels, apartments, condominiums, etc.
Class D:
Medical treatment, therapy, exercise lap swimming, wave or surf action, activity pools, splash pools, kiddy pools and play areas.

Pump: A machine that causes flow and pressure for filtration, heating, and circulation. Product suggestions: Sta-Rite Pump, Hayward Super Pump.

Rate of Flow: Quantity of water flowing past a designated point within a specified time.

Return Line: That part of the pool, spa or hot tub piping between the filter and the vessel through which filtered water passes.

Ring Buoy: Ring shaped floating buoy capable of supporting a user. Product suggestion:
Foam Ring Buoy.

Rope and Float Line: A line that connects at two ends of a pool and has buoys to separate either the deep and shallow ends, or create multiple lanes for lap swimming.

Sanitizer: A chemical agent used to remove unwanted contaminants.

Scale: The precipitate that forms on surfaces in contact with pool water when calcium hardness, pH or total alkalinity is too high. Be sure to use (NY180) Super Rust & Scale Remover if you encounter this problem.

Septum: The part of a pool filter consisting of cloth, wire screen, or other porous material on which the filter medium or aid is deposited.

Sequestering Agent: A chemical or compound that combines with dissolved metals or minerals in the pool water to prevent them from coloring the water or causing stains.

Shock Treatment: Adding high amounts of oxidizing chemicals to pool water in order to free up chlorine or bromine for sanitizing. Product suggestions: Blast Out, Blitz, Burst.

Skimmer: Any device, such as a surface skimmer, that collects surface pool water for filtration.

Skimmer Basket: A device that sits beneath the pool’s lid where it strains debris as the first line of defense in filtering the water.

Skimmer Net: A device constructed of netting attached to a telescopic pole that is used to manually clean a pool. Varieties include leaf rakes and the flat, “dip and flip” nets. Product suggestions: Leaf Skimmer, Premium Aluminum Leaf Rake.

Soda Ash (pH increaser): A white powder (Sodium Carbonate) used to raise the pH level in your pool or spa’s water.

Sodium Bicarbonate (Alkalinity Increaser): A white powder (baking soda) used to raise total alkalinity of pool water.

Sodium Bisulfate (pH Reducer): A dry, granular acid used to lower pH and/or total alkalinity in your pool or spa. Product suggestion: available in 6, 15 and 30 lb buckets.

Sodium Dichlor: A granular form of chlorine that is stabilized with Cyanuric acid that is used for shocking and superchlorinating pools. Product suggestion: Burst.

Sodium Hypochlorite: A clear liquid compound which has 5 to 16% available chlorine that is applied in swimming pools for water disinfection and oxidation. It works well as a long-term solution because microorganisms cannot build up any resistance to it.

Solar Heating System: Black solar panels of miniature plastic tubes through which pool water is pumped, absorbing the sun’s heat through convection as it passes through. These solar panels are often roof mounted with up & down plumbing connecting it. Both in ground and above ground systems available.

Spa: A hydrotherapy unit of irregular or geometric shell design that is not drained, cleaned or refilled after each use. It usually includes hydrotherapy jet circulation, hot water, cold water mineral baths, and air induction bubbles. Materials include but are not limited to plastic, concrete, and metal.

Stabilizer: A chemical that helps prevent the excess loss of chlorine due to sun exposure in your pool. Available in 2, 4 and 7 lb pails.

Strainer Basket: The second line of defense in maintaining a clean pool or spa is a basket at the pump. The holes for filtering water are smaller than those in a skimmer basket and prevent the pump impeller from clogging up.

Suction Outlet: The place at which water is sucked out of a pool or spa.

Suction Side: The plumbing prior to and carrying water to the pool’s pump. This side is under vacuum pressure.

Superchlorination: See Shock Treatment.

Test Kit: A kit containing strips, indicators, et cetera that are used to measure specific chemical amounts (such as pH, Hardness and alkalinity levels) in pools or spas. Check out our Water Testing section for all your needs.

Time Clock: Device that controls the periods that a filter, pump, heater, blower or other electrical device operates to efficiently manage your pool system.

Top Rail: The outer edge of an above-ground pool.

Total Alkalinity: TA affects and controls pH: If TA is too high, pH will be hard to adjust. If it’s too low, pH will be unstable and difficult to maintain. The ideal range is 80-150 ppm, depending on the interior pool finish. Product suggestions for control; Alkalinity increaser available in 5, 10 and 25 lb pails.

Total Chlorine: The sum of free and combined (Chloramines) chlorine.

Total Dissolved Solids (TDS): The amount of dissolved matter (including calcium, magnesium, carbonates, et cetera) in pool or spa water. To combat its accumulation, your pool or spa will need to be completely drained because TDS continually builds up over time.

Toxic: A chemical state in which a substance has an adverse physiological effect on living things.

TriChlor: A slow-dissolving tablet or stick composed of an organic chlorine compound which provides 90% available chlorine and has a pH of 2.9. Due to its slow-dissolving nature, it must be dispensed using either a floating feeder or an in-line chlorinator. TriChlor also prevents the chlorine from being destroyed by the ultraviolet rays of the sun with the help of cyanuric acid. Available in 1″ tablets (.5 oz), 3″ tablets (7 oz) and sticks (8 oz).

Turnover Rate: The amount of time it takes to completely circulate all the water in a pool or spa.

Underdrain: The lower collection system in a filter which directs filtered water back towards the pool. It also distributes water in reverse during backwashing. See laterals.

Underwater Light: A light fixture designed to illuminate a pool from below the water’s surface. Available in many colors to add a dÈcor effect. Product suggestions: Nitelighter In Ground Pool Lighting System, Aqua Luminator Above Ground Pool Light, NiteLighter Ultra Above Ground Pool Light.

Vacuum: Refers to the low pressure condition created in the suction line. Also refers to the cleaning process of sucking leaves, algae and other debris from the pool floor.

Valve: A device fit into a pipe that can either obstruct/limit the flow of water, or permit flow in one direction only.

Multi-port valve:
A type of valve that allows flow in a variety of directions (see multiple filter control valve).

Velocity: The speed at which liquid flows from one place to another.

Weir: The device in a skimmer that controls the amount of water coming into the skimmer as well as keeping debris inside. It is commonly referred to as that “flapper-gate thing.”

Winterized Liner: Plastic liners designed to tolerate exposure to severe winter temperatures.

Winterizing: The process of preparing pools and spas as well as all associated equipment (such as pumps, filters, solar panels and heaters) for winter. Be sure to check out our selection of Winterizing Chemicals, Winter Covers and Accessories.



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