Welcome to our Spa Glossary Page!

At Sonco Pools and Spas we have been selling and servicing spas for over 30 years. This experience makes us one of the few experts in the Midwest. If you're looking for information on spas, then you have come to the right place. Click on a term below for more information or ask us a question by filling out the form.

-- A

A liquid (muriatic acid) or dry granular (sodium bisulfate) substance used to balance water pH levels or to lower total alkalinity levels.

A durable, non-porous synthetic material used to form hot tub shell surfaces.

A powerful oxidizer derived from water, created when energy transferred into the water breaks apart water molecules. Active Oxygen completely breaks down waste and contaminants, leaving behind carbon dioxide and water. It does not leave behind chloramines or other byproducts that can cause hot tub water to be irritating to the skin and eyes, or to cause a strong odor.

Any water treatment product designed to kill algae.

Alkalis are substances with a pH greater than 7 that dissolve in water. They are the opposite of acids. Alkalinity refers to the amount of carbonates and bicarbonates in water, measured in parts per million (ppm). Total alkalinity is one of the components of balanced water.

Temperature of the immediate surrounding area.

-- B

In a Hot Spring spa, the effective filtration area of the filters is matched to the gallon per minute flow rate of jet pumps to ensure there is enough filtration area to filter all of the spa water, even when the jet pumps are on.

The desirable level of chemical composition in hot tub water. Key components of water balance are pH level, total alkalinity, calcium hardness and temperature.

The acrylic surface around the perimeter of the spa’s interior space.

Alkaline chemicals that counteract acid to achieve a neutral pH levelof 7.

A non-halogen sanitizer used for spa water.

A non-metallic element that is liquid at room temperature and soluble in water. Bromine is a halogen that bonds easily with other elements, has a strong bleaching action and is resistant to hot water with rapid pH fluctuations.  Like chlorine, it is often used in spa water maintenance.

-- C

The exterior surface of the spa.

An alkaline metallic element.

Also known as scale, this is a crystalline deposit that can form on spa water surfaces, equipment or pipes if water is not properly balanced.

A measurement of the dissolved calcium content of the spa water.  Can be tested by various methods and is reported as PPM of calcium carbonate.  Higher levels can lead to scaling or cloudy water problems and may require chemical treatment.

Used to trap debris before it reaches spa water. Filters should be cleaned or replaced regularly.

A chemical additive used to bind metals in water, prevent metal staining and water discoloration.

Foul smelling compounds in spa water formed by the combination of chlorine molecules, nitrogen and ammonia. The water must be shocked to get rid of them.

A member of the halogen family of sanitizers, used in spa water maintenance. When added to water, chlorine acts as an oxidizer, sanitizer, disinfectant, and all-around biocidal agent.

A switch that allows you to manually override an electrical circuit. This enhanced safety device automatically breaks the circuit when it detects harmful fluctuations in the electrical current.

Separate from the jet pump, this low amp pump pulls water from the spa and pushes it through filters before returning it to the spa.

The plumbing circuit that continuously moves water out of the spa and through pumps and filters before returning it to the spa. Circulation is a critical component in maintaining spa water balance.

A chemical used to bind suspended particles that cloud spa water. Similar to a flocculent.

Accessible from the inside or outside of the spa, the control panel allows you to adjust your spa’s settings such as temperature, jets and lighting.

The technology that determines how your spa operates.

A metallic element used in spa water treatment products as an algaecide.

Similar to aluminum sulfate, used to bind and coagulate particles in spa water.

The effects of an overly acidic water environment where alkalinity is too low. Corrosion can etch, pit or erode surfaces.

A cover removal system eliminates the need to drag off and pull on the spa cover before and after using your spa. It makes entry to your spa simple and helps prevent unnecessary damage to your spa’s cover.

Process in which acrylic sheet is bonded to an impact resistant ABS backing, ensuring consistent strength throughout the shell.

An exterior spa surface that can be customized with any material to blend with your outdoor environment.

Also called CYA, this is a stabilizing chemical used as a water conditioner to extend the efficacy of chlorine additives.

-- D

Any chemical or process that helps destroy harmful micro-organisms and other contaminants. Chlorine, bromine and sliver algaecides are examples of disinfectants.

A valve that can be adjusted to control the flow of water from the spa jets.

-- E

The total area, usually defined in square footage, of the filter cartridge(s) capable of filtering water.

A process that separates chemically bonded elements and compounds by running an electric current through them.

Natural compounds used in spa water treatments to break down and digest oily substances, such as sunscreen, that can enter the water.

Scientifically designed for greater user efficiency, comfort and safety.

-- F

A device used to remove solid particles from spa water by pumping it through a porous medium such as polyester fiber.

In spas that do not utilize an independent circulation pump to ensure continuous filtration, this is a regularly occurring interval in which the jet pump automatically turns on to circulate the spa water.

The rate at which spa water is pumped through a filter, typically measured in gallons per minute (GPM).

Chemical such as alum used to combine suspended alkaline material into a heavy gel that sinks to the spa floor where it can be vacuumed. Similar to a coagulant.

The amount of water that flows past a specific point during a specific period of time, typically measured in gallons per minute (gpm).

A term used to describe surface foam on your spa, it is caused by high levels of total dissolved solids (TDS) in the water combined with soft water and oils. Enzymes are typically used to control foam.

See also Polyurethane Foam or Urethane Foam. A polymer-based material that is typically sprayed to the underside of a hot tub shell to help retard the loss of heat escaping through the shell.

-- G

Grounded Fault Circuit Interrupters are required by the National Electrical Code in home electrical wiring for receptacle outlets installed for use with hot tubs, etc.

-- H

Any of the four elements fluorine, chlorine, bromine and iodine that are often used in spa water care.

Water that is high in dissolved minerals, specifically calcium, magnesium, or other salts that can corrode hot tub components and feel harsh to the skin.

The opposite of an air conditioner, a heat pump removes heat from the surrounding air through the use of cooling coils, then runs the air through condenser coils and transfers it as heat to the spa water.

The components inside the heater housing that create and transfer heat to the water.

Watertight unit that facilitates movement of water through and by the heater elements.

Short for horsepower, a non-metric measurement unit of power, typically associated with a mechanical device or engine. 1 unit of horsepower is equal to 745.7 watts.

The maximum horsepower a motor can produce continuously.

The maximum torque a motor can produce without abruptly losing motor speed.

Warm, moist air that can cause mold and mildew when present in excess amounts and combined with a lack of air circulation.

A non-chloride oxidizer and sanitizer used in biguanide systems. Can be used to shock spa water

Massage using pressurized water.

A family of liquid and granular chlorine compounds which release hypochlorous acid, a sanitizing agent, when they come in contact with water.

-- I

A quality management system designed to help organizations ensure they meet the needs of their customers and other stakeholders.  It is considered the highest international standard for design and manufacturing excellence.

A devise that generates copper, zinc and/or silver ions to kill bacteria and algae.

A metallic element that can be introduced to spa water through plumbing or well water. It can stain surfaces or turn water a clear green.

-- J

An outlet, such as a nozzle, used for emitting a high velocity stream of water. Jets affect the direction, volume and velocity of water flow.

Used to provide thrust to spa jets.

-- L

A process for layering and bonding different materials together to achieve greater strength, lower heat transfer and better sound absorption.

A system for determining water balance by assigning values to pH levels, total alkalinity, calcium hardness and water temperature. When all values are balanced, water will not be corrosive or scaling. Also known as the Saturation Index.

-- M

A metallic element which can cause spa staining and scaling when present in high non-chelated concentrations.

Natural substances such as calcium, copper, silver, iron and aluminum which can cause spa staining and scaling when present in high non-chelated concentrations.

Microscopic animal life that can be harmless, beneficial or harmful. Harmful micro-organisms can be removed from spa water with disinfectants such as chlorine, bromine and silver algaecides.

A diluted, liquid form of hydrochloric acid used to lower pH and alkalinity and to remove mineral stains and scale. Extremely caustic and corrosive.

-- N

When combined with chlorine, nitrogen creates undesirable chloramines in spa water, and is often introduced from sunscreen and perspiration.

A balanced filtration system that ensures all spa water passes through the filter before it re-enters your spa even when jets are on.

A granular form of potassium monopersulfate used to oxidize micro-organisms, chloramines and other contaminants.

A leader in public health safety, they have been helping people Swim Safer™ by meeting the needs of public health inspectors, product manufacturers, aquatic facility managers, facility users, and homeowners through a vast array of testing and certification services.

-- O

A shocking compound that removes or destroys built-up contaminants, chloramines and organic waste in spa water.

A colorless gas (O3) soluble in alkalis and cold water.  Its strong oxidizing capabilities make it a powerful organic oxidizer.  It can be produced with UV radiation, corona discharge (an electric discharge caused by the ionization of water surrounding a conductor, which occurs when the strength of an electrical field exceeds a certain value but is not great enough to cause a complete electrical breakdown), or by a chemical reaction.

A water care system that continuously injects millions of tiny, highly concentrated ozone bubbles into the water – neutralizing contaminants on contact.

-- P

A naturally occurring or synthetic compound consisting of large molecules made up of a linked series of repeated simple monomers. The type of polymer plastic material used in Hot Spring Spas Polymer Steps and ABS plastic substructure, is durable, weatherable, and long lasting.

The relative acidity or alkalinity of water, expressed in a numeric scale from 0-14, with low pH ranging from 0-6 (acidic), high pH ranging from 8-14 (alkaline), and 7 representing a neutral and desirable pH.

See also Foam Insulation or Urethane Foam. An insulating plastic material used to reinforce the shell of a spa for added support and to retard heat loss.

Short for Parts Per Million, this unit of measurement is used to express the concentration of chemicals in water.

Short for polyvinylchloride, PVC is a plastic used for plumbing pipes.

To cause a solid substance to be separated from a solution, as the result of a chemical action. Precipitates forced out of water will settle, stain, scale or remain suspended in water.

Part of the spa’s circulation system, a pump is a mechanical device, powered by an electric motor, which makes water flow under pressure.

Patented by Hot Spring, a pump shroud vents heat from the equipment compartment and transfers the heat back into the water, decreasing energy consumption. This also creates a cooler working environment for the motors and electronic components, contributing to a longer life for your Hot Spring Spa.

A removal basket on the suction side of a pump used to trap large debris such as leaves and prevent them from restricting water flow to the pump.

-- R

Chemical indicator used to test water balance.

The free available chlorine level that remain in a spa after initial treatment for contaminants.

-- S

A product used to kill bacteria or other micro-organisms in spa water. EPA recognized sanitizers approved for spas are chlorine, bromine, and biguanide.

A hard deposit of calcium carbonate that can attach to spa surfaces and equipment. Scale can damage heater effectiveness. Usually whitish in color, scale is the result of out of balance pH or alkalinity levels.

A chemical that bonds with metals to deter staining or discoloration. Similar to chelators.

The interior surface of the spa that holds both the water and the bathers.

The act of bringing spa sanitizer level up high enough to reach breakpoint chlorination, eliminate chloramines and achieve water purification.

Silver ions disinfect water so that micro-organisms like bacteria cannot cause disease.

The total number of designated seats.

Part of the suction side of a spa’s circulation system. A surface skimmer can help remove debris from the water’s surface.

Water that has a naturally or chemically-generated low calcium and/or magnesium content. Soft water can leave skin feeling silky.

A material that resists staining caused by minerals and is impervious to rust.

-- T

A strong, lustrous, corrosion-resistant metal with a silver color.

Short for Total Dissolved Solids, TDS is a unit of measurement for anything that can dissolve in water and be present in solution. High levels of TDS can over-saturate spa water and cause undesirable reactions and can ultimately result in the need to drain and refill the hot tub.

A range of products used to periodically test spa water for balance and sanitizing levels.

Paper strips used to measure spa water pH and other chemical balances.

Borate can be used in combination with sanitizers (chlorine, bromine and biguanide) to inhibit algae development. The combination of chlorine and borate may reduce chlorine consumption. In addition to suppressing algae growth, borate improves water clarity, reduces eye and skin irritation, and makes the water feel softer.

A chemical compound used as an industrial disinfectant and bleaching agent, usually sold in tablets or granular form and responsible for the strong chlorine odor often found in spas.

-- U

See also Polyurethane Foam and Foam Insulation. An insulating plastic material used to reinforce the shell of a spa for added support and to retard heat loss.

-- V

Devices placed on plumbing lines to direct, restrict or obstruct water flow such as the diverter valves used with spa jets.

-- W

The total number of gallons of water your spa can contain.

A pivoting flap, door or dam in a skimmer that prevents debris from re-entering spa water while allowing water to recycle through the filtration system.

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