Pool care has a language all its own. We've provided this glossary to help you understand some common pool care terms. Select a letter below to view a term.
The amount of acid required to lower pH and Total Alkalinity down to their correct levels.
A description of unbalanced water that is acidic and attacks and corrodes pool surfaces, fixtures and pipes.
Algae are airborne plant contaminants which are introduced by rain or wind and grow in colonies producing nuisance masses. Algae are not disease causing, but can harbour bacteria, and it is slippery. The most common pool types of algae are black, green and mustard. Maintaining proper chlorine (sanitiser) levels and shock treating will prevent its occurrence. Algae can interfere with proper filtration and greatly increase chlorine consumption.
Also more commonly called Total Alkalinity (TA). Alkalinity represents the amount of bicarbonates, carbonates and hydroxides in water. A measure of the pH-buffering capacity (it’s degree of resistance to change in pH) of water. The ideal range for TA is 80 – 120 ppm.
A chemical agent specifically designed and used to kill algae.
An aluminum sulfate compound, also known as settling salts, used (for pools) to cause suspended solids in the water to congeal into filterable masses (flocculate).
AUTOMATIC POOL CLEANER (APC)
An Automated Pool Cleaner is a vacuum cleaner intended to collect debris and sediment from swimming pools with minimum human intervention.
The amount of chlorine, both free and combined in the pool water that is available to sanitise or disinfect the water. Sometimes called residual chlorine or more commonly, free available chlorine (FAC). This is also the reading you will find on home test kits.
Invisible single-cell organisms of various forms, some of which can cause infections or disease.
The process of thoroughly cleaning the filter by reversing the flow of water through it, with the dirt and rinse water going to waste.
Water containing just the right amounts of Calcium Hardness, Total Alkalinity, pH and Dissolved Solids so as to prevent scale-forming or corrosive tendencies.
The calcium content of the water – it determines the hardness or softness of water. Too little calcium hardness makes the water corrosive. Too much calcium hardness in the water is scale forming. One of the factors which contributes to balanced pool water. Ideal range is 250 to 500 ppm.
The sanitising or chlorinating agent, Ca(OCℓ2), in HTH® Classic or HTH® Shock It. Chloramines are undesirable, foul-smelling, body-irritating compounds formed when insufficient levels of free available chlorine react with ammonia and other nitrogen-containing compounds (swimmer waste, fertiliser, perspiration, urine, etc.) Chloramines have an objectionable odour of "too much chlorine" and can irritate swimmers' eyes and cause skin irritation.
A term used to describe any type of chlorine compound used as a disinfectant in swimming pool water to kill, destroy or control bacteria and algae. Chlorine is a also an oxidising agent.
A term used in the trade to describe a condition where chlorine has slower killing speed on algae, bacteria and burning out organic matter. It is caused by over-stabilisation due to excess cyanuric acid.
The amount of chlorine required to destroy bacteria, algae and other contaminants in swimming pool water. Once the chlorine demand is satisfied, the water will be in a sanitary condition until further contamination takes place.
See Free Available Chlorine.
Also called coagulant or flocculant – A chemical compound used to gather (coagulate or agglomerate), or to precipitate suspended particles so they may be removed by vacuuming or filtration.
A water condition of low pH (acid condition) that can corrode metal pipes, pool fixtures and pumps. Could also etch plaster and cause eye irritation.
Also called stabiliser. It protects chlorine in the water from being destroyed by sunlight. Cyanuric acid, when used correctly, promotes cost effective pool maintenance. On the other hand, misuse of cyanuric acid may lead to chlorine lock or over-stabilisation.
Sodium bisulphate. A dry white crystal that produces acid when added to water. It is used for lowering pH and Total Alkalinity. Safe to handle and store.
Finespun filaments of glass which are available in a rope or mat form. It is a very smooth lining and is characteristically a neutral/acidic lining.
A device that removes undissolved or suspended particles from water by recirculating the water through a porous substance (a filter medium or element). The three types of filters used in pools and spas are sand, cartridge and D.E. (Diatomaceous Earth).
The operating time between cleaning or backwashing cycles of a filter. Also the amount of time the filter has water flowing through it each day expressed in hours.
A specified grade of silica sand which is used to filter out fine particles in the swimming pool water.
A device floating on the surface of the water in the pool containing a supply of chlorine, usually in tablet form, which is fed into the water over a period of time.
Also called coagulant or clarifier – A chemical compound used to gather (coagulate or agglomerate), or to precipitate suspended particles so they may be removed by vacuuming or filtration.
FREE AVAILABLE CHLORINE (FAC)
The amount of chlorine, both free and combined in the pool water that is available to sanitise or disinfect the water. Sometimes called residual chlorine or available chlorine. This is also the reading you will find on home test kits. Recommended level of free chlorine is 1.0 - 4.0 ppm. This provides protection against additional contaminants as they may be introduced into the pool.
A fitting in the pool or spa on the water return line from the equipment that water returns to the pool. Usually the last attachment on the return line.
A marbelite lining is a high strength cement coating.
This unit has 6 functions: filter, backwash, rinse, circulate, waste, closed . Through this unit the water may be sent to filter for normal filtration, backwash to thoroughly clean the filter, rinse to recompact the sand, circulate used to bypass the filter for maximum circulation, waste for draining of swimming pool water or the valve may be on the close position.
The build-up of cyanuric acid in swimming pool water, which usually results from the extended use of stabilised chlorinators in conjunction with stabilised shock products.
To "burn-out" undesirable solids, colour and odours. The pH is a measure of pool water acidity and basicity from 1 to 14. A low pH indicates an acid condition which causes swimmer discomfort and can corrode pool plaster and metal equipment. A high pH indicates a basic condition which promotes scale formation and causes cloudy water. The desired pH for pool water is in the 7.2 - 7.6 range.
A mechanical device, usually powered by an electric motor, which causes hydraulic flow and pressure for the purpose of filtration, heating and circulation of pool water.
The pump basket is the basket at your swimming pool pump which traps leaves, small stones, all organic or non-organic objects large enough to harm your swimming pool pump. Empty this basket once a week.
Parts per million or mgs/l. The parts by weight of a chemical or mineral per million parts of water.
A solid material which is forced out of solution by some chemical reaction and settles out as a visible deposit.
Position on multiport valve to be used straight after backwashing. The rinse function helps to recompact the sand in the filter.
Water is pushed through a bed of filter sand and removed through a set of lateral tubes at the bottom. Dirty water goes in the top and clean water exits out the bottom. As the filter sand becomes plugged with debris from the pool, the pressure increases on the filter and the water flow drops. In order to clean the filter, you just run it in reverse and dump the waste water; this is referred to as “backwashing” the filter. Once the filter is backwashed, you move to the rinse mode and that recompacts the sand and then back to filter.
A general term for a substance used as a disinfectant to kill bacteria and algae and oxidize organic contaminants.
The precipitate that forms on surfaces on contact with water when the calcium hardness, pH or Total Alkalinity levels are too high. Results from chemically unbalanced pool and spa water. Scale may appear as grey, white or dark streaks on the plaster, fibreglass or vinyl. It may also appear as a hard crust around the tile.
The practice of adding significant amounts of an oxidising chemical (such as HTH® Chlorine) to the water to destroy ammonia and nitrogen compounds or swimmer waste. It is the process of adding 3 x the normal dosage of chlorine and should be followed on a monthly basis as part of a regular maintenance programme.
A family of chlorine pool sanitisers that contain stabiliser (cyanuric acid or isocyanuric acid) to protect the chlorine from the degrading UV rays in sunlight – therefore promoting cost effective pool maintenance. Most common types are sodium dichloroisocyanuric acid and sodium trichloroisocyanuric acid.
STABILIZER See Cyanuric Acid.
A discoloration of a coloured deposit on the walls or bottom of a swimming pool or spa. Most often, stains are metals, such as iron, copper and manganese. They may appear as brown (iron), black (copper) or grey (manganese). They may even discolour the water. The metals get in the water because the pH is too low or someone has added a low-pH chemical directly into the circulation system. The low pH chemical dissolves a small amount of metal from the equipment. The metals begin to come out of solution as pH rises and deposit or stain the walls and bottom. Stains are sometimes confused with scale.
The practice of adding a sufficient amount of chlorinating compound to water to destroy chlorine demand compounds and any combined chlorine which may be present. Generally, the level of chlorine added is 10 times the level of combined chlorine in the water.
An apparatus or device used to monitor specific chemical residuals, levels, constituents or demands in pool or spa water. The most common pool and spa water tests are: pH, Total Alkalinity, Free Available Chlorine, cyanuric acid (stabiliser). HTH® 4-in-1 Test Kit tests the pH, Total Alkalinity, Chlorine and Acid Demand levels.
Small plastic strips with pads attached that have been impregnated with reagents that can be used to test pool water for residuals, levels, constituents or demands. The strips are usually dipped in the water, and the resulting colours of the pads are compared to a standard set of colours to determine concentration (HTH Quick Test Strips test pH, Total Alkalinity, Chlorine and Stabiliser levels).
TOTAL ALKALINITY (TA)
The total amount of alkaline materials present in the water. Also called the buffering capacity of the water. It is the water’s resistance to change in pH. Low Total Alkalinity causes metal corrosion, plaster etching and eye irritation. High Total Alkalinity causes scale formation, poor chlorine efficiency and eye irritation.
A measure of "free chlorine" and "combined chlorine" in pool water.
TOTAL DISSOLVED SOLIDS (T.D.S.)
Total dissolved solids (TDS) – A measure of the total amount of dissolved materials in the water. It is comprised of the spent or carrier chemicals added every time chemicals are added, as well as the hardness, alkalinity, chlorides, sodium, magnesium, calcium, etc. Maximum amount in pool is 2500 ppm. The only way to effectively lower TDS is to drain part or all the water and replace it.
TRICHLOROISOCYANURIC ACID (TRICHLOR)
A slow dissolving, tablet or granular, stabilised organic chlorine compound. Used for regular chlorination but must be dispensed using a floating feeder or an in-line feeder (chlorinator). Trichlor contains an ingredient (cyanuric acid or stabiliser) that prevents the chlorine from being destroyed by the ultraviolet (UV) rays of the sun. HTH® 4 in 1 Floater, HTH® Pace Floater and HTH® Pace Stabilised Pills are Trichlor products with 90% available chlorine.
This term can be used to define any number of devices that use suction to collect dirt from the bottom and sides of a pool or spa. Most common is a vacuum head with wheels that attaches to a pole and is connected to the suction line usually via the opening in the skimmer. It must be moved about manually and debris is collected in the filter.
The vinyl membrane that acts as the container to hold or contain the water. This type of lining is treated in the same manner as a fibreglass lining.
The weir is where your automatic pool cleaner hose gets connected. This is the link between the swimming pool pump and the automatic pool cleaner and it is where you insert your automatic pool cleaner pipes. The weir also prevents debris from floating back into the pool after the pump shuts off.
The weir basket is primarily responsible for catching the larger objects like leaves, small stones, all organic or non-organic objects large enough to harm your swimming pool pump. It is highly recommended that this basket be emptied weekly.