How-To Guides | Spa Simulator



Go Ahead!  Start our Amazing Spa Simulator
Visualize exactly how a hot tub works.

Our interactive schematic diagram is a visual insight into a hot tub's plumbing, filtration, circulation systems, and jets, as explained in more detail below. It's much more than a water flow diagram!  Even if you never perform service on your own spa, a basic understanding of its inner-workings will likely make ownership a more carefree experience in the long run. (Pump location may vary).

Advice: If you are going to be away from your computer for a period of time, Dr. Tubbs recommends that you switch off the pump motor and air blower control buttons above, to conserve electrical power.

Control System

Digital keypad Today's spas have digital topside keypads from which various hot tub functions, including jet pump or spa pumps, light, and heater can be controlled and programmed.  (Earlier spas used air buttons for these functions).
This keypad is connected to the spa's Control System, a box which regulates the functioning of various devices.  The Control System or spa pack and associated components are located in your hot tub's equipment bay.  Most spas have removable access panels attached with screws, as depicted in our Spa Simulator video.
Need hookup information?
Hot Tub Wiring Explained
How to wire a hot tub

Filter Systems: Suction and Pressure Types

All hot tubs have something in common: they recirculate, heat, and filter water.  But various brands do this in slightly different ways, primarily dependent upon the type of filtration system used.  Your spa will have either a suction filter, which means it is connected before the spa pump's intake, or a pressure filter which is connected after (hence it's pressurized by the pump).

Regardless of the spa filter type, water is basically taken from the surface, pumped through the heater, and returned to the spa via a network of plumbing tubes connected to jets. Both system types can provide excellent water filtration, although systems with floating Weirs have superior surface skimming.

Suction skimmer Suction Filters
The majority of today's spas have suction filter systems, which are always top mounted for easy cartridge access.
These come in two basic varieties.  Pictured above is a floating Weir which automatically telescopes to the spa's surface water level to skim impurities.  The Weir unscrews to expose the filter cartridge inside.  Belize Spas use telescoping Weirs.
The other variety of suction filter incorporates a skimmer basket, which houses one or more drop-in or screw-in (threaded) cartridges. skimmer basket
Pressure filter cannister Pressure Filters
Many spas still use pressure filters.  In these systems, the filter cartridge is housed in a sealed canister, rather than incorporated with a surface skimmer.  The skimmer (water intake) is a separate unit by itself.
The earliest spas had base-mounted pressure filter canisters, accessible only by opening up the spa's equipment compartment.  Modern versions have top-mounted canisters, designed for easier filter cartridge changing from the spa-side.

Pump & Heater

Hot tub water is drawn from the surface, as well as from one or more suctions in the footwell, to the spa pump.  (Most spas have at least one 2-speed pump; some have more than one pump).

Water now flows through a  heater housing* where it is warmed to the desired temperature. This assembly contains a resistance heater element as shown here. heater assembly

The heater system incorporates a pressure or flow switch, and an overheat high-limit switch.  These are safety devices to cut heater element power, should water flow be restricted or overheating occur.  The water temperature is controlled at the topside keypad, up to a maximum of 104°F (the legal limit).

*NOTE: Some systems are plumbed with the pump located after the heater.

Pump Replacement  Heater Testing


air induction jets The warmed water now flows through large PVC tubing to one or more water manifolds, where it is distributed via many smaller tubes to the jets.  Better spas have fully adjustable, directional air-induction jets of various sizes, with different attributes.

Air Induction

air control valve Today's spas incorporate air-inductions jets, which mix warm water with air in the user's desired proportions using a topside control.

Better manufacturers, including Belize Spas, draw free waste heat from air in the equipment compartment  (from the pump motor) to improve heating efficiency.  High quality air-induction jets preclude the necessity for a separate powered air blower, further saving energy.

Air-induction jets have both a water connection, and an air Venturi connection.  The rate of air flow to the jets is regulated by a topside air control valve (or it can be shut off altogether if desired).  Like the water, air is also distributed to the various jets via a manifold, as shown in our Spa Simulator video. Jets of hot tubs


A spa ozonator (ozone generator) is connected by small diameter tubing to either an injector Venturi or to a special ozone jet, which is low in the spa water for maximum water contact, and which draws the ozone in by suction.  Notice that the ozone tube loops above the hot tub's water line.  This is called a Hartford Loop, which along with a check valve helps to prevent water from backing into the ozonator.

Modern electronic UV ozonators are extremely reliable and effective. Operated by the control system, ozonators are only on during operation of a hot tub pump circuit.

Adding an ozonator is not a necessity, but can help reduce chemical usage and significantly improve water quality.  Ozone is not a primary sanitizer, and cannot be used all by itself to keep hot tubs safe and healthy (contrary to what some ill-informed salespeople may tell you).  It works with your sanitizer for better water quality by oxidizing contaminants and organic material.

Electronic UV Ozonator by Clarathon Many of today's better spas come ozone-ready, so adding an ozone generator such as our state of the art Clarathon Electronic Ozonator Kit is easy and inexpensive.

All About Ozone  Installation Directions


Most spa lights operate on 12 volts, and are controlled at the topside keypad. The bulbs can easily be changed if the socket is located behind the equipment access door.

color changing LED light bulb with rainbow of colors The hot tub's standard incandescent light bulb can be swapped out for a multiple-LED digital color lighting unit at a very modest cost.

Digital Color Spa Light


Most spas have a drain bib (a plastic faucet) inside the removable access panel. Some spas have no drain and must be siphoned.  drains for hot tubs

Air Blower

An electric air blower is essentially a vacuum cleaner in reverse. They force air via a manifold through many tiny orifices drilled in a spa shell or through small air-injector fittings, rather than mixing air with water via air-induction jets.

Hartford Loop Blowers should be installed with their delivery hose in a Hartford Loop above the waterline, as well as with a blower check valve on the wet side, to prevent water from backing into the unit and causing an electrical short.

Although popular years ago, most contemporary spa manufacturers have abandoned powered air blowers. The advent of high efficiency air-induction jets has made them unnecessary. Blowers also rapidly cool down the spa, especially in winter, which wastes the energy necessary to reheat the water.

Power Service

Full-sized acrylic spas operate on a hard-wired, GFCI-protected 220-240V service. The wiring enters the equipment compartment through a hole drilled through the spa side or toe kick, as shown in our Spa Simulator. (110V Plug-n-Play spas usually have a GFCI device attached to the end of their power cord, and are plugged into a dedicated outlet).

IMPORTANT: Consult your owner's manual for electrical hookup requirements. Working around electricity and water is dangerous. All electrical work must be performed by a qualified electrician in accordance with the National Electrical Code and in compliance with local codes. Consult your local building/electrical department for details, permits, and required inspections.