All Swim

The All Swim Glossary Of Hot Tub Terms

Caldera Utopia Spas hot tubsChoosing your Hot Tub can (and should) bring up lots of questions. With so many options to choose from, how do decipher what features you will benefit most from, or indeed what the feature even means exactly?

  • Why do some tubs feature Ozone?
  • What is an Air Blower for?

The list goes on. So we’ve put together a nonsense-free, simple Glossary of the most common Hot Tub features and terminology – so you can easily understand and identify the key features you want in a tub.

A is for Air Blower

Hot Tub jets typically use a mixture of water and air to produce a massage effect. An Air Blower is a separate motor from the pump motor, which works by pushing large volumes of air through specific jets. The Air Blower can be turned on or off using a dedicated control, which produces a bubbling effect for a lighter type of massage than water-only massage jets.

Bear in mind that the use of an Air Blower will offer a variation in the massage effects, but the air will also have a cooling effect on the air (impacting energy costs due to the call for heat).

B is for Balboa

A familiar name that will come up frequently in the world of Hot Tubs. Balboa is the name of Balboa Water Group, who are recognised as one of the industry leaders in the production of hot tub control panels and topsides. One thing to consider, Balboa control panels alone do not determine the overall quality of a hot tub (as they can easily be retro-fitted to a wide range of tubs), so if you are considering a tub featuring Balboa controls, be sure to check out the full details and warranty information of the tub and the manufacturer.


A popular sanitiser for use in Hot Tubs which is an alternative to chlorine and works exceptionally well at high temperatures.

C is for Cover & Cover Lifter

Lifestyle Coverlifter ProLift IIA well-fitting rigid insulation cover will maximise heat retention in your tub and although not essential, a cover lifter makes taking the cover off and replacing it easier and protects the cover.


A sanitiser that is available in either stabilised or unstabilised forms. Stabilised chlorine is a slow release sanitiser and comes in granular or tablet form whereas unstabilised chlorine (known as Shock) quickly raises the level of sanitiser to kill off bacteria – ideal for treating fresh water or when sanitiser levels have dropped too low resulting in less than desired water quality.

D is for Diverters

The ability to divert power between seats in your hot tub is very useful; for example if there are only 2 of you sat in a 6 seater, diverter valves allow you to turn off the power to the empty seats, diverting it to the area of the tub being used.

Or for those times when you’re enjoying chatting but no longer need your massage jets on – you can just turn your jets off and remain in the tub.

E is for Energy Efficiency

One of the most frequent questions people ask when browsing our tubs is ‘How much is it going to cost me to run?’ A key question indeed. Caldera Spas models are designed to be highly energy efficient, through a combination of features such as the unique FiberCor insulation (on Caldera Spas) and EnergyPro circulation and heating system.

Realistically, monthly running costs come in at around £30-35 per month based on around 7 hours use per week.

F is for Frogs

A set of cartridges that sit within your Caldera Spas tub (in a built-in hidden compartment) that look after your water quality. The mineral cartridge softens the water while the Bromine cartridge delivers a constant level of sanitiser keeping your water clean and safe. Fully adjustable so you can increase or decrease the level as needed.


Used to reinforce the acrylic shell once it is removed from the mould.

Filter Cycles

The programmed time period when the hot tub water filtration comes on (e.g. twice a day at 12 hourly intervals).

G is for Ground Preparation

When planning the location for your hot tub, be sure to properly lay the correct foundation. A concrete slab is the ideal base, measuring 4 inches (10cm) in thickness and it should be completely flat and level.

H is for Hot Tub Circuit Therapy

Hot tub circuit therapy, the Caldera Spas differenceNot the type of ‘circuits’ you may have experienced in the gym – but a way more relaxing circuit. Caldera Spas have designed their tubs to encourage the bather to spend time in every seating position, resulting in a full body hydrotherapy massage that targets every muscle and stress point.

No more lounger-hogging!

I is for Insulation

One feature that appears across all 3 Caldera Spas ranges is the FiberCor Insulation, which is 4 x denser than traditional hot tub insulation foam. This makes it 4 x better at both heat retention with an added bonus being a quieter operation when the tub is on.

J is for Jets

Not all jets are created equally, and quantity doesn’t always equal quality! We recommend wet-testing any hot tub you are considering purchasing. Even if the exact model can’t be tested, trial a model from the same range or manufacturer.

Caldera Spas models all feature jets exclusive to Caldera, as they have created their own series of jets based on providing the highest quality of massage benefits for the user.

K is for kW (heater size)

The output measurement of a heater, usually ranging from 2-3kw in a hot tub. The higher the kW output the quicker your hot tub water will heat up, with average heating time around 12-18 hours from scratch.

L is for Loungers

An angled seat that enables you to recline in the hot tub. Some tubs feature one or multiple lounger seats whereas others offer more seats by not having a lounger at all.

M is for Music

Some tubs feature in-built music systems allowing you to Bluetooth music from your chosen device. Caldera Spas offer the option of having music or not in their tubs, so customers have the choice (great for when you already have an outdoor music system setup!).

N is for ‘No Flow’

An indicator that water is not flowing through the hot tub pump. Refer to your manual or contact your retailer for advice.

O is for Ozone

Although you will always need to use some form of sanitiser to kill off and prevent bacteria in a hot tub, it’s helpful having something that reduces the amount of chemicals required. Caldera Spas feature Monarch CD Ozone, which mixes ozone bubbles into the water as it travels through a special contact chamber - neutralising contaminants and reducing the need for additional sanitiser. A key benefit of the Monarch CD form of ozone is that it does not contain a UV light that needs regular replacement to remain effective.

P is for Pumps

The pump is what drives water up through the pipework and forces it out via the jets. Smaller hot tubs typically have 1 pump (driving up to 30 jets or so). Larger tubs will usually have 2 pumps.


The measure of acidity or alkalinity above the neutral pH of 7.0. Anything below 7.0 is considered acidic and above is alkaline. For hot tubs your pH should be maintained between 7.2 – 7.6.


Parts per million is the measure of concentration of a chemical.

Q is for Quality Assurance

Purchasing a hot tub is a big decision, so naturally you’ll want to feel confident in the quality of both the tub itself and the retailer. Some key points to look for are the Warranty details of the tubs, the reputation of the manufacturer and the company selling the tub.

Similarly, buying a tub from a manufacturer who has been in operation for a long time is a good sign of quality – such as Caldera Spas who have been creating quality tubs for over 40 years. A good quality manufacturer will be reflected in the warranties they offer on their tubs also.

R is for Rotomolded

DreamMaker rota moulded hot tubsRotomolded hot tubs are solid, one-piece tubs that are extremely durable and rotationally constructed from plastic. Due to the one-piece construction, these tubs are very strong, lightweight and will never rot, rust, chip or crack. Also a cheaper option than traditional tubs. Why not view our rotomolded DreamMaker and Fantasy Spas hot tub ranges?

S is for Sanitiser

This is what keeps the water clean, safe and free from bacteria. The most commonly used options are bromine or chlorine.

T is for Test Strips

A simple method of testing your hot tub water; a strip is dipped into the water then by reading the colours against the colour coded chart on the bottle to identify any action you need to take to balance the water.

U is for Underwater Lighting

Many tubs feature LED underwater lighting which can enhance the ambience in your hot tub.


An exclusive massaging system featured in some of the Utopia models by Caldera Spas, the user can select a variety of massage sequences to fully customise the hydrotherapy massage.

V is for VersSage

A powerful jet featured on the Paradise and Utopia ranges by Caldera Spas that can be adjusted to provide a variety of massage effects. The more you angle the nozzle, the wider the path of rotation.

W is for Watkins Wellness

The US organisation currently the global leader in producing hot tubs founded in 1977. Part of the MASCO Corporation – a Fortune 500 company listed on the New York Stock Exchange. Watkins manufacture two leading hot tub brands; Fantasy Spas rotomolded tubs and all three ranges by Caldera Spas (Vacanza, Paradise and Utopia).

X is for ‘X’-Display Deals

It’s always worth checking if there are any deals to be had on ex-display models as sometimes it can result in a real bargain.

Y is for You Time

A major benefit in owning and using your hot tub is having time dedicated to relaxation and stress relief. Regular hot tub use is proven to decrease stress and tension and to promote muscle recovery along with general wellbeing.

Z is for Zzz's

How does hot tub use improve sleep quality? Spending time in water temperature raises core body temperature. When you exit the tub, the resulting drop in your body temperature signals it’s sleep time to the brain, setting you up for a better quality night’s sleep.

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