Acrylic:	A plastic that is used to form the tub in 95% of all spas. The acrylic is molded in the desired shape, and is backed by several layers of fiberglass reinforcing, sometimes in conjunction with additional bonding layers. Currently available in two finishes; a high gloss called "marble" and a matte finish called "granite".
Air Injectors:	In addition to jets, some spas offer a blower system that injects air bubbles into the spa to enhance water movement.
Blowers:	See Air Injectors
Bromine:	See our Spa Chemistry Guide
Chlorine:	See our Spa Chemistry Guide
Full Foam Insulation:	A process of insulating a spa by injecting foam between the tub and the skirt. Generally used as a structural component of the spa, full foamâs major drawback is that it must be dug out to effect any repairs, decreasing the structural integrity of the spa.
Misters:	An option offered by some companies, such as Catalina, that when activated produces a cooling mist across the entire top of the spa.
Nature2 System:	An passive non-electrical device that releases trace elements of silver and zinc into the spa water, adding an additional level of sanitation to the tub. At a cost of approximately $30 dollars, it must be replaced every 4 months. Used along with an ozonator, the need for standard spa chemicals is reduced to virtually zero.
Neck Jets:	A therapy jet specifically placed and designed to relieve neck tension.
Ozonator:	An electronic device that exposes the water to ultraviolet light, breaking the molecules apart temporarily forming a gas called ozone that purifies water, reducing the chemical requirements. Most better spas either include ozonators or offer them as an option. HIGHLY RECOMMENDED
PowerPro Jets:	A patented jet manufactured by Jacuzzi that produces up to 2.5 times the flow of a standard spa jet.
Quarite:	A brand name for granite finish acrylic.
Skirts:	The exterior of the spa. Usually made from redwood, cedar or mahogany, although some spas offer a resin or polyurethane skirt. They may or may not be a structural component of the hot tub.
Spa Pack:	The electronic control center of the spa, consisting of the control box and topside control panel. The spa pack electronically regulates and monitors all spa functions, including jets, temperature, air injectors, filter cycles, freeze protection, etc.
Therapy Jets:	Jets are the heart of any spa. Their purpose is to move water in a concentrated stream. Therapy jets are placed to move water against different parts of the body. As the name implies, their purpose is to provide massage therapy.
Thermal Wrap:	A process of insulating a spa using a high density removable material. Sometimes used in conjunction with a "dead air" space, the same principle used in thermos bottles. Generally preferable to full foam insulation.
Venturi:	A system of control valves that distribute and mix air and water into the jets. Used to regulate jet pressure, one venturi generally controls a "bank" of jets.
Whirlpool Jets:	In addition to therapy jets, some spas include whirlpool jets: These are generally large volume jets that are designed strictly to move water, creating a circular flow in the tub.