Glossary of Terms
D - G
I - O
P - R
S - Z
Acid - A chemical
compound which releases hydrogen ions into water, decreasing pH. Products like muriatic acid or Lo 'N Slo are used
to lower pH and Total Alkalinity in pool water.
Acid Demand - The amount of
acid needed to lower pH to the proper level for pool water.
Aeration - The process of mixing
air and water. In a spa this can happen two ways: 1) Using an Air Blower to force air into an air channel or through
the spa jets. 2) With Venturi Air Controls which allow air to be pulled into and mixed with the water the spa jet.
Algae - Microscopic plants deposited
in pool or spa water by wind, rain, and dust. They thrive in sunlight and warm water, clogging filters, increasing
the need for sanitizers and oxidizers, and causing slippery surfaces. There are 21,000 known species of algae.
Algicide - A chemical added
to water to kill algae infestations and prevent their recurrence.
Algistat - Any substance that
retards algae growth.
Alkali - A basic solution that
Alkali Demand - The amount of
alkali (base) needed in the water to raise pH and/or Total Alkalinity to the proper level.
Alkaline - When the pH of a
solution measures above 7.0 on the pH scale. Alkaline (often referred to as "basic") is the opposite
Ammonia - A nitrogen-containing
compound that combines with free chlorine to form chloramines.
Backwash - Reversing the flow
of water through the filter to clean the elements and filter medium. Typical maintenance for sand filters and some
Backwash Cycle - The time needed
to backwash (clean) the filter and its components.
Bacteria - Single-celled microscopic
organisms. Pathogenic bacteria can cause infections, disease and bather irritation. Chlorine and Bromine are used
to kill bacteria in pool & spa water.
Balanced Water - Pool or spa
water that has a proper pH and the appropriate mineral content to prevent corrosion and scaling.
Base - See Alkali.
Bather - In a Spa, a bather
is anyone using a spa for a duration of 20 minutes at 102 F.
Bather Load - The number of
people in a pool or spa at a particular time or during a specific period of time.
Biguanide - A long chain polymeric
molecule with both bactericidal and algicidal characteristics (such as SoftSwim® B). Must be used in pool maintenance
with a supporting oxidizer (such as SoftSwim® C).
Biofilm - The accumulation and/or
colonization of bacteria, algae, mold, fungus and other micro organisms on the surface of the pool/spa.
Borate - An elemental mineral
used for conditioning water to provide clearer, more comfortable water.
Breakpoint - During chlorination,
this is the point at which all combined chlorine is oxidized (removed) and only Free Available Chlorine remains
in the water to kill bacteria. This point is achieved when Free Available Chlorine is 10 times higher than Combined
Bromamines - Non-irritating
bromine-ammonia compounds that have some degree of sanitizing capabilities.
Bromide - An inactive ion that
can be activated to hypobromous acid by some means of oxidation, either with chlorine, ozone, or oxidizing shock.
Bromine - A chemical used in
various compound forms to kill bacteria in pool & spa water. Hypobromous Acid is the active killing agent that
all bromine compounds form when dissolved in water.
Buffer - Chemicals that serve
to prevent fluctuations in pH (see Total Alkalinity).
Calcium Carbonate - Scale that
forms from calcium compounds when pool water is too alkaline, calcium hardness is too high or total alkalinity
is too high. These hard deposits accumulate on pool surfaces and equipment.
Calcium Chloride - A soluble
salt added to pool water to raise the calcium hardness level.
Calcium Hardness - The amount
of dissolved calcium in pool water. Low levels of calcium hardness will promote deterioration in the pool surfaces
and equipment. High levels will promote scale formation.
Calcium Hypochlorite - A chlorine compound using calcium as the carrying
salt for application.
Cartridge - A porous, replaceable
element in some filters. Particulates are removed when they penetrate into the medium. Particulates are retained
on the surface of the cartridge for removal. Loose debris can be hosed off, oils must be chemically removed by
soaking the cartridge.
Chelant - A chemical compound
that 'ties-up' iron, copper, or calcium to prevent staining and scaling. Also called a sequestering agent.
Chloramines - Substances formed
when chlorine combines with swimmer wastes (nitrogen or ammonia), causing chlorine odor and irritation to skin
and eyes. This compound has little sanitizing value compared to active chlorine.
Chlorine - One of five members
of the Halogen family of chemical elements. It is the most widely used bacteria-killing agent for recreational
water treatment. Two forms of chlorine are used: (1) Organic chlorine - less vulnerable to the UV rays of the sun
and therefore longer lasting. (2) Inorganic chlorine- susceptible to degradation by the UV rays of the sun and
therefore less convenient for pool use. Also see Hypochlorite.
Chlorine Demand - The amount
of chlorine required to be added to the water before a free chlorine residual can be maintained. Both dissolved
and undissolved organic and inorganic debris can contribute to a chlorine demand.
Chlorine Generator - On-site equipment that generates its own supply
of chlorine, hypochlorous acid or hypochlorite for water treatment. The chlorine is typically generated from Sodium
Chloride (salt) by exposing it to a low voltage (DC) electrical current.
Chlorine Neutralizer - A compound
used to neutralize excessive chlorine in a water sample in order to permit more accurate testing of the water balance
factors. It can also be used in the pools and spas themselves to neutralize high levels of Chlorine or Bromine.
Chlorine Residual - The amount
of chlorine left to kill new bacteria entering the pool after is has been sanitized. It is the chlorine level present
after the chlorine demand has been satisfied.
Coagulant - A polymeric chemical
compound added to water to gather suspended particles together for filtration. SpaGuard Water Clarifier and PolySheen
Blue are coagulants.
Combined Chlorine - Chlorine
that is in combination with ammonia, nitrogen, or other organic compounds. See Chloramines.
Contaminated - An impure condition
indicating the presence of bacteria, algae or other undesirable matter in water.
Corrosion - Etching, pitting
and other destructive erosion of the spa surfaces and equipment due to low pH or other chemical imbalance.
Cyanuric Acid - A chemical compound
added to pool water to reduce the degradation of chlorine by the UV rays of the sun. Also referred to as CYA, stabilizer,
Diatomaceous Earth (DE) - A
powdery filtering agent composed of the skeletal remains of a form of plankton (diatoms). Used in Diatomaceous
DPD #1 - A test reagent (typically
a tablet) used to measure the amount of Free Available Chlorine or Total Bromine in the water.
Dry Acid - Safer to handle than
Muriatic Acid, it lowers the pH or Total Alkalinity. Lo ‘N Slo® is a dry acid.
Effluent - The water that flows
out of a filter, pump or other device.
Filter - A device that removes
undissolved particles from water through a porous filter medium (sand, cartridge, DE).
Filter Cycle - The operating
time between filter cleaning or backwash cycles. Long filter cycles are the most convenient.
Filter Element - A device (cartridge)
within a filter tank designed to entrap solids and allow the flow of water through the filter back to the spa.
Filter Medium - Sand, Diatomaceous
Earth, or other finely graded material used to filter particles out of the water.
Filter Sand - Sharp silica or
quartz particles graded for uniform size and used as a filter medium. #20 Silica Sand is the industry standard
grade of filter sand.
Flocculant - A chemical compound
added to water causing suspended particles to sink. Once on the bottom of the pool the once suspended particles
can now be vacuumed to waste.
Flow Meter - A measuring device
that determines the gallons per minute of water flow through a pool circulation system.
Flow Rate - The volume of liquid
(water) flowing past a given point in a specific time period, expressed in gallons per minute.
Free Available Chlorine - Hypochlorous
acid, the chlorine in pool water that is not combined with ammonia or nitrogen, and therefore available to kill
bacteria entering the water. See also Available Chlorine.
Gelcoat - The colored surface
layer of a fiberglass pool or spa shell. This resin is applied to the mold during the manufacturing process.
Gunite (shotcrete) - A concrete
and sand mixture sprayed into a reinforced steel form to create a pool shell. Plaster, paint, or some other form
of cosmetic finish is applied on top of the gunite structural shell.
Halogen - A family of chemical
elements containing Chlorine and Bromine, and widely used for a variety of sanitizing situations.
Hot Tub - A wooden vessel, containing
hot moving water. First popularized on the west coast by cutting wine barrels in half, the hot tub market rose
and fell in popularity with the advent of vacuum formed thermoplastic materials. Mass production of Hot tubs has
employed the use of varied types of wood from redwood, cypress, teak, and other exotic tropical hardwoods.
Hydrogen Ion - The positively
charged nucleus of a hydrogen atom. Increasing levels of the hydrogen Ion in the water will cause pH to be lowered.
Hydrogen Peroxide - An oxidizing
solution typically used as a liquid shock treatment and clarifier for biguanide pools.
Hydrotherapy Jets - A spa fitting that blends air and water creating
a high-velocity, turbulent stream of air enriched water.
Hydrotherapy Spa - A non-wooden
vessel containing hot moving water for therapeutic use to ease stress, muscle strains and other physical problems.
Popular construction types include thermoplastic shells and gunite/plaster interiors.
Hypobromous Acid - The most
effective form of bromine in water for disinfecting.
Hypochlorite - An inorganic
(unstabilized) family of chlorine compounds used in various forms to provide chlorine for water treatment. Includes
calcium hypochlorite, lithium hypochlorite, and sodium hypochlorite.
Hypochlorous Acid - The active
sanitizing compound formed when any type of chlorine is put in water.
Impeller - The "heart"
of the centrifugal pump. Rotating veins create the suction flow of the water into the pump.
Influent - The water entering
a pump, filter, heater, or pipe.
Inorganic Chlorine (Unstabilized Chlorine)
- A form of chlorine that is vulnerable to degradation to the UV rays of the sun. See Hypochlorite for forms of
Leaching - The process of extracting
a mineral from plaster interiors or tannic acid from wooden hot tubs.
Liquid Chlorine - Sodium Hypochlorite
solutions added to water as a disinfectant. Characteristics include very low levels of available chlorine, high
contribution to Total Dissolved Solids, a high pH, and inconvenient to apply and handle. Should not be confused
with Clorox® with even lower levels of available chlorine.
Make-Up Water - Fresh water
used to fill the pool or spa. Also called Source water.
Muriatic Acid - See acid.
Nitrogen - An element that when
combined with chlorine forms chloramines. Common in rainwater, cosmetics, oils, perspiration, and urine.
Organic Chlorine - A form of chlorine
that contains cyanuric acid/stabilizer/conditioner.
Organic Matter - Contaminants
derived from living organisms. Including leaves, cosmetics, urine, perspiration, bugs, animals, and other bather/environmental
debris. Organic compounds are any which contain carbon.
Orthotolidine (OTO) - A test
reagent used to measure the amount of Total Chlorine in pool water. In the presence of increasing levels of chlorine
it turns yellow to amber in color.
Oxidation - A chemical process
for removing breaking down organic compounds.
Ozone - A gaseous molecule composed
of three atoms of oxygen. Ozone is
created for oxidation of water contaminants. Its instability and short life in the water require that it be used
only to supplement chlorine or bromine to control bacteria.
pH (potential Hydrogen) - A
measurement that indicates the acidic or basic nature of a solution. Measured on a scale from 0 to 14, the ideal
pH of pool/spa water should be 7.4 to 7.6. A pH of 7.0 is neutral. A pH below 7.0 is acidic. A pH above 7.0 is
Phenol Red - A reagent (dye)
for measuring the pH of water in a range from 6.8 to 8.2. It changes color from yellow to purple in color as the
pH goes from 6.8 to 8.2.
Plaster - The interior finish
of a gunite (concrete) pool or spa. Usually composed of white marble dust and portland cement.
ppm - Parts per million, a unit
of measurement used in measuring chemical application. It indicates the amount, by weight, of a chemical in relation
to one million parts by weight of water.
Psi - Pounds per square inch.
The unit by which filter pressure is measured on a pressure gauge. Psi increases as the filter gets dirtier.
Precipitate - Solid particles
forced out of solution by a chemical reaction. They may settle on the bottom of the pool or spa, or remain suspended
in the water giving the water a cloudy look.
Precoat - The coating of Diatomaceous
Earth placed on the grids/fingers of a DE filter at the beginning of each filter cycle.
Pump - A motor-powered mechanical
device that creates pressure and water flow by spinning an impeller to provide circulation through the filter other
system components. Some spas combine a pump for filtration/heating with an additional "'therapy pump".
Reagent - Chemical testing compounds
that are used to test for chlorine, bromine, pH, total alkalinity, calcium hardness, etc.
Saturation Index (SI) - A numeric
value indicating whether water is scale forming or corrosive. It factors in pH, Total Alkalinity, Calcium Hardness,
and water temperature.
Scale - Mineral deposits that
form on pool and spa surfaces and equipment due to excessive calcium in the water. Scale is more likely to form
in heated water, especially on the heater element or heat exchanger, if proper water balance is not maintained.
Shock Treatment - The addition
of an oxidizing compound to the water to chemically break-up (oxidize) contaminants such as suntan oils, cosmetics,
perspiration, metal ions and wind-blown dirt which interfere with normal sanitizer performance and/or cause cloudy
or colored water.
Skimmer - A device in the pool
or spa wall that continuously removes the surface water and floating debris to be taken away by the filter. A hand
skimmer net can be used manually to "dip" large floating debris from the water.
Sodium Bicarbonate - Added to
water to increase the Total Alkalinity. The water treatment grade of Sodium Bicarbonate is used in pool water.
The baking grade (baking soda) is used for cooking. The two grades do not share the same physical characteristics,
and should not be interchanged.
Soft Water - Water that contains
less than 100 ppm of calcium and magnesium.
Superchlorination - The addition
of a sufficient amount of chlorinating compound (usually 3 to 5 times the usual dosage) to the pool water for the
destruction of chlorine demand compounds and any combined chlorine which may be present.
Stabilized Chlorine - An organic
chlorine compound used to sanitize pool water and favored for its economy and ability to remain active in the presence
of strong sunlight. (NOTE: non-stabilized chlorine such as liquid chlorines or drum chlorines are rapidly lost
in water when exposed to sunlight.
Stabilizer - Cyanuric acid;
a compound that prevents the dissipation of chlorine to the ultraviolet spectrum of the sun, BioGuard Stabilizer
Surfactant - The word surfactant
comes from its description: Surface Active Agent. It applies to any chemical compound that can decrease the surface
tension of a liquid (water). When you add a surfactant to pool water, it helps the water penetrate the cracks and
crevices where algae hide (and of course, the water brings the FAC and any other algae-killing chemicals with it).
Total Alkalinity - A measure
of the water's ability to resist pH change due to the presence of these compounds in the water.
The information on this page has been provided courtesy of BioLab,
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