Chemical and Water Balance Terms

ACID
Liquid (muriatic acid) or dry granular (sodium bisulphate) substance used to lower the pool's pH (toward a more acidic condition) or to lower total alkalinity levels.

ALGAE
Over 20,000 species known to man!  Algae may form on your pool surfaces or it may bloom in suspension.  We typically know algae to be green, but it may also be yellow (mustard algae), black, blue-green or any shade in between.  It may form separate spots, or seem to grow in sheets.  Pink algae, is not algae at all, but a form of bacteria.  Algae are living, breathing organisms that need warmth, sunlight and CO2 (carbon dioxide) to thrive.

ALGAECIDE
Meaning: to kill algae.  Algaecides perform best as a backup to a routine sanitation program.  They also help to kill airborne spores as they blow into the pool.  A variety of algae treatment products are available including copper and silver compounds, poly-quat compounds, chlorine enhancers, and herbicides.

ALKALINITY
Alkaline refers to the condition where the water's pH is above 7.0 (7.0 is referred to as neutral) on the pH scale.  It is the opposite of acidic.  Alkalinity is the amount of carbonates and bicarbonates in the water, measured in ppm of Total Alkalinity.

ALUMINUM SULPHATE
Also known as alum, this product is used as a flocculant, which attracts suspended particles in the water together (green or cloudy pools).  Alum sinks everything to the bottom, which is then vacuumed to waste.  A small amount of alum can also be used as a sand filter additive.

BACTERIA
From a health perspective, the most dangerous microorganisms that can be found living in pool water.  Some are pathogens, which can cause infectious diseases.

BACTERICIDE
Kills bacteria.  Chlorine is both a bactericide and a germicide.  Silver "algaecides" are actually more of a bactericide, and are particularly useful to treat pink algae.

BALANCED WATER
Balanced water is the result when all of your chemical parameters are where they should be, and thus "balance" each other.  The key components of water balance are pH, Total Alkalinity, Calcium Hardness and Temperature, as measured using the Langelier Index of water balance.

BASE
Those chemicals of alkaline nature, which will counteract the pH of an acid, eventually neutralising at 7.0.  Common bases used around the pool would include Soda Ash, Sodium Bicarbonate, Sodium Carbonate and Sodium Sesquicarbonate.

BREAKPOINT CHLORINATION
When you shock treat your pool, the goal is to reach a high enough level of free chlorine, measured in ppm, to break apart molecular bonds, specifically the combined chlorine molecules.  When breakpoint is reached with sufficient additions of chlorine, everything in the pool becomes oxidised.

BUFFER
A base such as Sodium Bicarbonate (Baking Soda), added to your pool will increase alkalinity which increases the buffering capacity of the pool; or, your pool's resistance to pH change.

BUFFERING CAPACITY
The ability of the pool to resist changes in pH, which prevents water balance.  The buffering capacity is given by the alkalinity, a close cousin to pH.  If your pH bounces, or resumes previous levels soon after adjustment, your buffering capacity is too low.  If this occurs check your total alkalinity.

CALCIUM CARBONATE
Known as scale, crystalline deposits of calcium may form on your pool surfaces, equipment, or even line your pipes like cholesterol in your arteries.  Properly balanced water can prevent this.

CARBON DIOXIDE
A gas, which when present in the water, provides necessary food for the growth of algae.

CARBONATE
Primary in the make up of total alkalinity and TDS (Total Dissolved Solids).

CHLORAMINES
The chlorine molecule is strongly attracted to nitrogen and ammonia.  When either of these combinations hook up, they form a chloramine, which are undesirable, foul smelling, space taking compounds that require shocking the pool water to get rid of them.

CHLORINE
When added to water it acts as an oxidiser, sanitiser, disinfectant and all around biocidal agent.

CHLORINE, free available
Free available chlorine is that which is active, not combined with an ammonia or a nitrogen molecule, and ready to react to destroy organic material.

CHLORINE, combined
That portion of total available chlorine left over when free available is subtracted.  The measure of chlorine which has already attached itself to other molecules or organisms.  Most of this is made up of chloramines.

CHLORINE, total available
The sum of free available and combined levels.  With Poolpride Pool & Spa Test Strips, one can determine the free available level, then total available.  The difference, if any, is the level of combined chlorine.

CHLORINE DEMAND
The quantity of free available chlorine removed during the process of sanitising.  The organic and non organic material contained in the water will "demand" a certain level of oxidiser to be destroyed.

CLARIFIER
A clarifier is a chemical used as a coagulant of suspended microparticles.  Helps the filter by clumping smaller particles into filterable sizes.  Poolpride Liquid Floc is a clarifier.

COAGULANT
The properties of a chemical used in the assemblage and precipitation of suspended material that may make the pool appear cloudy.

CONTAMINANTS
Any microparticle or organism, which reduces water clarity or quality, or presents health hazards.

CONDITIONER
Also called Cyanuric Acid (CYA) or stabiliser, this chemical provides a shield from the sun around the chlorine molecule, extending the efficacy and therefore saving you money.

CORROSION
The effects of an acidic pool environment, one in which the pH is very low.  Corrosion in the form of etching, pitting or erosion of pool equipment and surfaces is the result.

CYANURIC ACID
A granular chemical added to the pool water, which provides a shield to chlorine for protection from UV radiation, which disrupts the molecule and destroys its sanitising ability.

DISINFECTANT
Chemicals or processes, which work to destroy vegetative forms of microorganisms and other contaminants e.g. chlorine.

DIRECTIONS
What you should read before using any chemicals.

DIRT DEMAND
The demand that your pool has for dirt.  This level is inversely proportional to available time for cleaning.  If you remove the dirt from the pool, you have created a dirt deficit, and the pool will actually suck dirt out of the air to maintain its dirt demand.

DRY ACID
Sodium bisulphate, a granular form of acid, used to lower pH and alkalinity in the water.  Safer and less caustic than muriatic acid.  Available as Poolpride pH Decrease.

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

FLOCCULANT
Essentially the same as a coagulant, this chemical (such as alum) is used to combine suspended alkaline material and/or algae into a heavy gel, which sinks to the bottom for vacuuming.  Available as Poolpride Liquid Floc.

HALOGEN
A member of the family of elements: fluorine, bromine, chlorine and iodine.

HARD WATER
Water which is high in calcium hardness and other salts which prevents soap from lathering.

HYPOCHLORITE
A family of chlorine compounds such as Calcium Hypochlorite and Lithium Hypochlorite (both granular) and the liquid Sodium Hypochlorite.  When these compounds contact water, they release Hypochlorous Acid, the active sanitising agent.

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

IRON
Usually introduced into the water from iron plumbing or from well water, Ferric Iron can stain surfaces, while Ferrous Iron will turn your water a clear green color.

LANGELIER INDEX
Also called the Saturation Index, Mr. Langelier devised a system to determine water balance by assigning values to levels of pH, Total Alkalinity, Calcium Hardness and Water Temperature.  When all parameters are in balance, the water will be neither corrosive or scaling.

MINERALS
Such as Calcium, Manganese, Magnesium, Nickel, Copper, Silver, Iron, Cobalt or Aluminum.  Their presence in high non-chelated concentrations can lead to stains & scale when conditions are right.

MICROORGANISM
A living, breathing creature in your pool.  The purposes of disinfectants are to remove such "infectants".

MURIATIC ACID
The liquid dilution version of Hydrochloric Acid used to lower pH and alkalinity, and to remove mineral stains and scale.  Extremely caustic and corrosive.

NASCENT OXYGEN
A single oxygen atom, not yet bonded to anything.  Extremely powerful oxidiser when harnessed correctly.

NITROGEN
When combined with chlorine, nitrogen creates chloramines, which are not desirable for your pool.  Nitrogen can be found in many "swimmer" wastes (perspiration, suntan oil, hair tonics etc) but can also be introduced by other means.

OXIDATION
The "burning up" of organic waste and compounds in the pool water.  It also refers to what you may see on your metal pool surfaces if your water is corrosive.  Rust is a form of this kind of oxidation.

OZONE
The molecule containing three atoms of oxygen; known to be a very powerful sanitiser.  Ozone producing equipment creates this molecule by UV radiation or corona discharge generators.

pH
The scale of relative acidity or alkalinity, expressed in logarithmic numbers from 0 - 14, with 7.0 being neutral.  What's really being measured is the hydrogen ion concentration.  Some would say pH stands for Power of Hydrogen.

PPM
Parts per million.  A method of assigning value to certain concentrations of chemicals in the water.  For example, alkalinity should be kept at 120-150ppm for pools treated with Chlorine Granules or Pills and 150-200ppm for pools treated with Stabilised Chlorine Granules, Pills or Tablets.

PRECIPITATION
To precipitate is to come out of solution; become insoluble by result of chemical action.  Material forced out of solution, purposefully or accidentally, will then settle, stain or scale, or remain suspended in the water.

QUATERNARY AMMONIUM COMPOUND
A type of algaecide composed of ammonia compounds.  Effective algaestat for green and blue/green algae.

RESIDUAL
Usually refers to free available chlorine levels remaining in the pool after initial treatment or activity with contaminants.

SANITIZER
A chemical agent used to remove unwanted contaminants.

SCALE
Usually whitish in colour, scale forms on pool surfaces and equipment when mineral salts are forced out of solution.  A scaling condition is one in which calcium hardness, pH and/or alkalinity levels are out of balance.

SHOCK
As a noun it loosely describes the products used in shocking, such as hypochlorites.  As a verb it describes the act of bringing the sanitiser level up so high that breakpoint chlorination is reached.  When breakpoint is reached, a "shock" is sent through the water, tearing apart molecules and cell walls.

SODA ASH
A base used to counteract an acidic condition by raising pH.

SODIUM BICARBONATE (baking soda)
Another base, however its properties will increase alkalinity more than pH.  Used to raise Total Alkalinity levels.

SODIUM HYPOCHLORITE
Liquid chlorine used in pools, identical yet stronger than Clorox bleach.

SODIUM TETRABORATE
New technology that renders algae incapable of processing carbon dioxide, which they need to live.

SODIUM DICHLOR
A granular form of chlorine that is stabilised with Cyanuric Acid.  Used for shocking and superchlorination.

STABILISER
See Cyanuric Acid.  Stabilisers, also called conditioners and can be added directly to your pool to extend your chlorine efficacy.  Cyanuric Acid is already added to Poolpride Stabiliser.

TOTAL ALKALINITY
The ability of the pool water to resist changes in pH.  The "buffering" capacity of the water.  Additions of Sodium Bicarbonate will increase the levels, expressed in ppm.

TOTAL DISSOLVED SOLIDS (TDS)
A measure of everything that has ever dissolved in the water; all the matter that is in solution.  High TDS levels can oversaturate your water, causing all sorts of reactions.

TURBIDITY
Cloudy, dull, hazy water, due to microparticle suspension.

ULTRA VIOLET LIGHT TREATMENT
Using UV wavelength radiation to destroy contaminants in water.  UV light is also used to create ozone molecules for the same purpose.

Pool Structure & Equipment Terms

AIR BLEEDER ASSEMBLY
Located on the top of the filter and sometimes accompanied by a pressure gauge, the bleeder is opened to release air trapped in the filter.

AUTOMATIC POOL CLEANER
A device, which agitates or vacuums debris from the walls and floor of the pool.

BACKWASH
The process of thoroughly cleaning the filter medium and/or elements by reversing the flow of water through the filter to waste.

BALL VALVE
A device with a hollowed out ball inside which can be turned with an external handle to decrease or increase flow.

BLOWER
Plumbed into the spa return line, air is injected to produce "fun" bubbles and a hydrotherapy effect in the spa.

BOOSTER PUMP
Secondary to the filter pump, a booster pump is used to power an automatic pool cleaner such as Polaris or Letro.

BTU
British Thermal Unit.  A unit of measurement for the use of gas by a gas appliance.  Pool heaters are rated by their consumption.

CAPACITY
The volume of water a pool can hold.  Measured in litres.

CARTRIDGE
One type of filtration, the cartridge is a pleated, porous element through which water is passed through.

CHECK VALVE
A one way flow device.

CHLORINATOR
Devices which allow for the safe, controlled introduction of chlorine into the water.

CIRCUIT BREAKER
A switch, which allows manual override of an electrical circuit.  It also automatically breaks the circuit when current fluctuations are detected.

CIRCULATION SYSTEM
The "circuit" of plumbing which continuously carries the water out of the pool, through the pump & filter, and returns it to the pool.

CONDUIT
A pipe, usually grey PVC or flexible PVC designed to carry wires from a source (i.e. time clock) to a load (i.e. pump motor).

COPING
The capstone on top of the bond beam, which finishes the edge around a pool or spa.  It may be precast concrete or brick.  On vinyl liner pools pre-fab coping is usually part of an integrated system for the wall, vinyl liner and deck.

COUPLING
A plumbing fitting designed to join two pieces of pipe.

COVERS:

Automatic covers:  Solid, reinforced vinyl which rolls onto a reel at one end of the pool and attaches on the sides using small aluminium tracks.  Can be motorised or hand crank.  Some models may snap the sides into small anchors placed into the deck, providing more shape flexibility.  Provides safety (with water pump off), debris protection and heat/chemical/water retention.

Hard Covers:  A cover which rests on the edge or coping of the spa or small pool.  Provides a barrier to debris and possibly people, while keeping the heat trapped in.

Solar Covers:  Sometimes called a thermal blanket, this cover floats on the surface, magnifying the sun's rays to warm the water and also enhance chemical/heat/water retention.

Winter Covers:  A barrier to sun and debris, winter covers secure the pool from contamination.  Two examples of winter covers are:

Mesh Covers:  These stretch tightly across the pool like a trampoline.  They are the only covers which can be called safety covers in that the mesh polypropylene allows precipitation to pass through.

Solid Covers:  These are usually made of some form of plastic or vinyl and are secured around the edges either by aqua blocks or similar weight or the edges attach to anchors set in the concrete or wooden deck.

DIATOMACEOUS EARTH
The filtering medium of the DE filter, this dry powder is the fossilised remains of the ancient plankton, diatom.

DIATOMACEOUS EARTH FILTER
A filter tank containing fabric covered grids which hold the DE powder up against the flow of the water.

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.

DRAIN
Also called the main drain, this plumbing fitting is the start of one suction line to the pump and is usually situated at or near the centre bottom of the pool.

EFFLUENT
The water that flows out of the pump, on its way through the filter, heating and treating equipment, and returning to the pool.  Also known as the pressure side.

ELBOW
A 90 or 45 degree plumbing fitting.  Used where your pipes take a turn.

FILTER
A device used to remove particles suspended in the water by pumping water through a porous substance or material.

FILTER ELEMENT
A device inside a filter tank designed to entrap solids and direct water through a manifold system to exit the filter.  Cartridge filter elements and DE filter grids are two examples.

FILTER MEDIUM
A finely graded material, such as sand, diatomaceous earth, polyester fabric or anthracite coal that removes suspended particles from water passing through it.

FILTER PUMP
The device that pulls water from the pool and pushes it through the filter on its way back to the pool.

FILTRATION RATE
The rate of water pumped through a filter in litres per minute (lpm).

GAS VALVE
An electronic valve in the pool heater that directs gas flow from the meter to the pilot and the burner tray.

HEAT EXCHANGER
A set of 8 or 10 ribbed copper tubes that absorb the heat produced below it and transfer it to the water cycling through its tubes.

HEAT PUMP
The antithesis of the air conditioner, the heat pump's cooling coil removes heat from the air while the condenser coil transfers it to water cycling through it.

HOT TUB
Usually considered to be a circular, wooden vessel filled with heated and circulated water.

HYDROSTATIC PRESSURE
A force involving built up ground water, which creates upward pressure beneath the pool shell.

HYDROSTATIC RELIEF VALVE
Fitting(s) installed in the floor of the pool designed to manually or automatically release hydrostatic pressure beneath the pool by allowing ground water into the pool.

IMPELLER
The rotating vanes of a centrifugal pump; its action creates the flow of water.  The impeller is shaft driven by an electric motor.

INFLUENT
The water coming into and up to the impeller from the suction lines.  These pipes are under vacuum pressure.

JET PUMP
Used in spas to provide additional thrust into the hydrotherapy jets.

LATERALS
Elongated, capped plastic nipples at the bottom of a sand filter which are slotted to allow for water passage while keeping the sand in the filter tank.

LOAD
An electric device, which consumes energy, placing a load on the source.

LOW WATER SUCTION
An influent fitting, typically low on the wall in the deep end of a vinyl liner pool.  A cheaper alternative to a main drain.

MECHANICAL SEAL
A seal behind the impeller, which prevents water from running out along the shaft of a motor.  AKA: pump seal.

MULTIPORT VALVE
A 4 or 6 position valve combining the functionality of several valves into one unit which has revolutionised pool plumbing.  The six common functions are described below:

  1. Filter:  This is normal water flow through the filter, say, top to bottom. This is where the valve sits 99% of the time.

  2. Backwash:  When the pressure gauge indicates, you will need to backwash the filter.  When the handle is turned to backwash, the flow through the filter is reversed, more often than not, bottom to top.  The effluent water (out of the filter) is directed to the waste line.

  3. Rinse:  After backwashing, it's a good idea to rinse for 15-20 seconds to remove any residual dirt that may return back into your pool after backwashing.  The rinse cycle flows through the water in the same direction as the filter, say, top to bottom, but effluent is sent out the waste line.
  4. Recirculate:  This setting bypasses the filter, water coming into the multiport does a U-turn and heads back towards the pool.  Used only when the filter is broken (at least it's circulating), or when adding speciality chemicals which specify using this setting.
  5. Drain/Vacuum to Waste:  This useful setting allows you to vacuum up large volumes of debris that would either clog the filter or pass through it because of its small size.  Dirt that is vacuumed passes right out the waste line.  It is also the setting of choice when draining the pool or lowering the water level (if you didn't need to backwash, which also lowers the water level).

PLASTER
A common type of interior finish applied over the concrete shell of an inground swimming pool.

PRESSURE CHECK
A test for the rate of water flow; also a test for leaks in plumbing by placing the line in question under pressure and waiting for the pressure to drop.

PRESSURE GAUGE
A device indicating pressure in a filter system.  Provides a determination of how the system is operating, and informs you when service is required.

PRESSURE SIDE
The return side of the plumbing.  The section from the pump impeller towards the pool.

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.

PLUNGER
The sliding disc assembly that changes valve position in a push-pull valve.  For example - up for backwash, down for filtration.

PUSH-PULL VALVE
A two-position valve used for backwashing sand or DE filters.

SAND FILTER
A filter tank, usually fibreglass or ABS plastic, filled with sand and gravel.  The pump diffuses water over the top of the sand bed, and forces it through the sand and into the laterals on the bottom.

SKIMMER
A surface skimmer is a plumbing fitting set at water level, containing a weir mechanism and a debris basket.  The skimmer is part of the suction side circulation system.

SKIMMER BASKET
Beneath the lid, the basket strains debris, as the first line of defence in filtering the water.

SKIMMER NET
Attached to a telescopic pole, a leaf rake is a very useful tool in keeping the pool clean.  Also called a skimmer net are the flat, "dip and flip" nets, which aren't so useful.

STRAINER BASKET
The second line of defence is a basket at the pump.  The holes in this are smaller than those in a skimmer basket, and prevent the pump impeller from clogging up.

SOLAR SYSTEM
Black mats of miniature plastic tubes through which water is pumped, absorbing the heat as it passes through.  These mats are roof mounted with up & down plumbing connecting it.

SUCTION SIDE
The plumbing prior to and carrying water to the pump. This side is under vacuum pressure.

TEE
A plumbing fitting used to bring two pipes together into one, or vice-versa.

TEST STRIPS
What you should use frequently to determine the water balance in your pool.

TURNOVER
The amount of time it takes your pump to move all the water in your pool through the filter and back again.  Usually, pools are designed for an eight-hour turnover.

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.

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

VINYL LINER
One type of interior finish.  The liner is draped over a sand or cement floor, and locked into the top of the wall.

WEIR
The device in a skimmer that controls the amount of water coming into the skimmer, and keeps debris inside.  That "flapper-gate thing".

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