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Blog posts tagged with 'hot tubs'

I need a replacement hot tub filter cartridge, what do I do?

Finding replacement hot tub filter cartridges can sometimes be a challenge, especially if you’re unfamiliar with the make and model of the spa or need a filter for an older model. Don’t worry though, we stock a vast range of popular filter cartridges at our hot tub showroom here in Cardiff, if we don’t have your particular hot tub filter we can source a vast range of other makes and models from our trusted network of suppliers.

Does your filter have a manufacturers code?

Perfect! This is usually the easiest way to identify the make and model of filter cartridge you require. Look for a manufacturers code on one of the ends of the cartridge and this will help us source a replacement item for you relatively quickly.

I don’t have a code, but I have my old filter cartridge.

If you can’t find a manufacturer’s code on your hot tub filter we can still source a replacement for you based on a few simple measurements of your old filter. Firstly measure the outside diameter (OD) of the hot tub filter cartridge and the inside diameter (ID) of the hole in the middle of the cartridge.

Next, measure the length from the outside of the cartridge (not including any raised steps, handles or threads).

Measuring the OD and ID of your hot tub filter Measuring the length of your hot tub filter


Lastly, if your hot tub filter cartridge doesn’t have a hole at each end, just let us know what type of end caps it has. Other types of tops will either be a handle or closed (flat). For the bottom, your filter may have a slip fit collar, coarse thread (SAE) or fine thread (MPT) collar.

Ideally, to help us match your hot tub filter cartridge, a few photographs always helps us to identify the correct replacement for you. Or, if you are planning on visiting our hot tub showroom in Cardiff, bring your old filter with you and one of our trained sales staff will help identify the correct cartridge for you.

I don’t have a code or an old filter cartridge. What now?

Without an old filter cartridge or part code the simplest way of sourcing a replacement is by providing us with the make, model and year of manufacturer of your hot tub.

Remember, we are able to source a huge range of hot tub filters and our website has a small selection of the cartridges we stock. If you need any help or advice please call one of our friendly sales staff to discuss your specific needs on 029 2070 5059.

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.

A sure sign of a reputable retailer is to check if they are BISHTA members. BISHTA is a trade organisation that represents the British and Irish Hot Tub and Pool industry and its’ members are committed to a code of ethical practices and selling with integrity.

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.

Caldera Spas hot tubs, a unique hydrotherapy experience

Discover the Caldera difference for yourself

Caldera Spas Lumbarssage massage seatWith such a bewildering array of hot tubs on the market place it can be a little daunting as a first time buyer (or even a second or third time buyer looking to upgrade) to make a choice that’s going to be right for you, after all, hot tubs are a luxury purchase for most of us and it’s important to know you’re choosing one that’s going to offer something unique and give you the best possible experience for your money.

That’s where we think our Caldera Spas, and in particular our Utopia range, sits head and (soothed) shoulders above the competition. This incredible range of hot tubs includes an industry redefining approach to total body restoration through hot tub circuit therapy.

So what is Hot tub circuit therapy?

Well, hot tub circuit therapy is a bit like having a personal trainer in the gym. A personal trainer helps you create a plan that’s designed to move you from station to station with different exercises to give your body a balanced, full body workout helping to target all the major muscle groups.

Just think of your Caldera Spa as a personal hot tub therapist with each seat and position individually designed to provide a deep, relaxing massage for different muscle groups. Instead of sitting in one position like you would in most hot tubs our Caldera Spas encourage you to use the whole hot tub for relaxation. As you move around the spa the invigorating jet design and layout focuses on individual muscle groups, from neck and shoulders through to the large muscles of your back, lower back and even down to your hamstrings, calves and feet - often overlooked regions of the body when it comes to other hot tubs but if you spend most of your working day stood up you’ll really appreciate this aspect of the hot tub circuit therapy experience!

What's different about the hydrotherapy jets on Caldera Spas

The design and layout of the jets on any hot tub is the crucial element to your experience as a user and you won’t find a greater attention to detail or such a meticulous focus on the quality of the hydrotherapy experience than on our Caldera hot tubs. Each area of the hot tub has been specifically designed to target a particular muscle group and here are the massage clusters that will really help ease those aching muscles and gently soothe those tensions away.

Caldera Spas hydrotheray massage jets


Featured on either the seat or lounger, this targets your neck, shoulders and middle back.

Atlas Neck Massage

A contoured pillow that cradles your head while specialised, above the water line jets focus on your neck and shoulders.


Multiple jets focussing on the large muscles in your back. Importantly, some models feature jets that target wrists and calves.


A unique jet configuration that helps relieve tension and pain in your back’s lumbar region.

Euphoria Jets

These jets provide a deep, penetrating massage to your thighs, knees and calves and feet and you’ll enjoy two of these incredible feature jets in most Utopia models.

Hip Jets

These jets work on this often overlooked stress point and helps re-invigorate movement in this area of your body.

Angled Calf Jets

Working on the often overlooked muscles in your lower leg, perfect for those who spend most of the working day stood up.

Sole Soothers

Jets that stimulate and revive the muscles in your feet that help relieve the tension in the area of your body that bears your full weight all day.

The proof really is in the testing

Hopefully this brief glimpse into the most important features of our Caldera Spas has given you a valuable insight into the attention to design detail that these hot tubs offer, they really are a cut above the rest. But don’t take our work for it, we have a complete range of Caldera hot tubs, including the fabulous Utopia series, on display at our award winning showroom here in Cardiff. Why not arrange a visit? Our trained, knowledgeable sales staff are always on hand to help you explore this unique range of hot tubs and understand the benefits of hydrotherapy massage and we also have changing facilities on site so you are always more than welcome to book a wet test to try them for yourself. Be warned though, every customer that has tried these incredible hot tubs has made a purchase. That is surely proof enough of the Caldera difference!

How to look after your hot tub

My New Hot Tub Has Arrived – What do I do now?

Hot tub commissioning with All SwimAssuming you purchased your new hot tub from a reputable supplier, you will have benefitted from having it properly installed and commissioned as part of the delivery service. A part of that service likely included having the hot tub filled with water and treated with chemicals, and a demonstration of how to use the control panel to operate the tub properly.

Great as that is, many new hot tub owners find it a little tricky at the beginning to maintain proper water balance and in the day to day operation and maintenance of the tub - in fact we always tell our customers we expect to be on hand to answer any questions or concerns in the post-delivery first few weeks!

Getting To Know Your New Hot Tub

As with any new item, it always pays to spend some time at the start familiarising yourself with the operating instructions. That way, you can enjoy using your tub as and when you want to – minus the headache of frantically scanning the user manual trying to figure something out at the last minute, when you’re expecting guests (haven’t we all been there at some point?!)

Some of the common queries we receive from new tub owners include:

Why Is My Hot Tub Not Heating Up?

The first thing to double check if you encounter a problem with your hot tub not heating up is the operating mode the tub is set on. Hot Tubs typically have three modes; Standard, Economy and Sleep (or Ready and Rest depending on the manufacturer). Here’s a brief explanation of what each mode means:

Standard: In standard mode the set temperature will be reached and consistently maintained.

Economy: In this mode the heater will only come on when the tub is in one of its standard filter cycles (typically for 1.5-2 hours twice a day, morning and evening) if the temperature is below the set temperature. Economy is ideal for daily users.

Sleep: Working on the same principle as Economy mode, but in Sleep mode the drop in temperature usually has to be 10 degrees below the set temperature for the heater to kick in during the filter cycle. Sleep mode is most commonly used when going on holiday or periods of absence where nobody will be using the tub.

I’m Struggling To Maintain Correct Water Chemistry

The most common query we receive by far from new hot tub owners is due to cloudy or murky water along with how much of each chemical they should be adding and when. And it’s no surprise, as there is a lot to get to grips with, particularly if you have never owned a hot tub before! High usage and being unfamiliar with water testing and chemical dosing are the usual causes of incorrect water chemistry during the first few weeks.

Some tips we offer are to get in the habit of regularly testing the water using the testing strips in your chemical starter pack. This will help you to understand when the water is calling for higher levels of sanitiser or pH adjusters etc, and it’s a habit that will save you stress and money over time.

Did you know that the ideal time to add sanitiser is after use, not before? This way, the sanitiser gets to work straight away on cleansing and cleaning the water – whereas if left until the following day, bacteria has had a whale of a time already starting to multiply overnight – beat it at its’ own game!

Factors that will increase the need for sanitiser are users not showering prior to use or removing make up (fake tan loves to make a filter cartridge work hard too). So, it’s a good habit to adopt from the start asking bathers to rinse off before using the tub – you could even get a little sign printed if you don’t like asking, or forget to ask.

Keeping a close eye on your pH level is important too, as if the water becomes too acidic or alkaline it can make for an uncomfortable user experience, and take its toll on the hot tub equipment.

What Do I Need To Do With Spa Frogs?

Spa Frog bromine and mineral cartridges Our range of Caldera Spas have in-built water care courtesy of a Bromine Spa Frog cartridge and Mineral Frog cartridge. One is prefilled with Bromine to sanitise the water, reducing the need for sanitiser top-up dosing by up to 50% and the other with minerals, which condition the water for a softer feel.

You control how quickly these are administered into the water via a simple dial on the cartridges, allowing you to increase or decrease the level as needed (ideal for a weekend away, simply turn up the dial for automatic Bromine sanitisation!)

Frequency of changing Spa Frog cartridges depends on how you set the dials, and changing the cartridges is straight forward; ensure all jet pumps are turned off before opening the cap of the in-built housing compartment. Turn the handle counter-clockwise and lift the holder up and out before setting the dial on the new cartridges and inserting them into the holder. Secure them back into place by pushing the compartment down and twisting it clockwise, then close the cap.

How Often Should I Change The Water?

BISHTA guidelines recommend changing the water in your hot tub at least every 3 months, more frequently in the case of high usage.  This will help to ensure optimum water quality and protect both bathers and the hot tub equipment.

Top Tip; Prior to emptying your tub, it is recommended to use a ‘flush’ such as Hot Tub Flush to thoroughly clean all of the internal pipework, removing debris and any bacteria lurking within.

Changing Filter Cartridges

As a guide, your filter cartridges should be removed and cleaned every 2 weeks or so, depending on usage. This can be done either by soaking them overnight in a cleaning solution like our Blue Horizons filter and cartridge cleaner or by using an instant solution eliminating the need to soak like the All Swim instant filter cleaner following the usage instructions on the label. New cartridges should be replaced approximately every 6 months.

Cleaning The Hot Tub

Hot tub commissioning with All SwimRegularly cleaning the surface of your hot tub will help keep the exterior in tip-top shape and help minimise scratching or marking the acrylic shell, while keeping it looking great. Surface cleaners such as our Lo-Chlor Spa Shield are great for polishing up the surface of the shell, simply combine with a soft microfibre cloth to buff the shell, taking care not to get the product in the water. When changing the water, take advantage of that time to give the entire shell a clean before you refill with fresh water to keep it looking good as new (just ensure there is no residual product on the surface before refilling.)

You’ve Got It Sussed!

Hopefully the above tips will prove useful when it comes to taking care of your hot tub and you can also find more information on our Frequently Asked Questions page that may be of interest. For any queries or areas of concern, if in doubt, check it out with your supplier or give us a call on 02920 705059 for further help and advice.

What you get for your money when buying hot tubs

How much should a Hot Tub cost?

Caldera Spas Utopia Series hot tubs The simple answer to that question is, it depends on the hot tub! If you’re completely new to hot tubs you may be considering an inflatable spa for around £500. With a small initial outlay these hot tubs are a great way to see if you and your family are suited to a hot tub lifestyle. Upgrading from this price point you may be considering a rota-moulded hot tub that typically start from around £3,500 and, at the other end of the spectrum, are the very best portable hot tubs commercially available that can exceed £15,000. The reason for the differences in prices is down to size, features, manufacturing materials, design, the performance that the hot tub delivers and the type of manufacturer’s warranty offered.

Perhaps a more important consideration is what you actually value in a hot tub. When you’re spending time relaxing in your hot tub do you want to be worrying about how expensive it is to run or how well insulated that cabinet really is for the money you paid? Do the quality of the hydrotherapy jets matter to you and that troublesome lower back pain you’ve been suffering with? Or maybe including multicoloured lighting and a waterfall in the price will really make a difference to your planned entertainment needs? Well, to help you make the very best decision when considering a new hot tub here’s our guide to the key features you’ll find on a hot tub and how they can affect the price.

How size affects your hot tub price

Generally speaking the larger the hot tub you are considering, the higher the price is likely to be. This comes down to the fact that more materials are going to be needed to build a larger spa along with a need for more jets, larger, more powerful pumps and even filters with increased filtration capacity. All of these factors determine cost and don’t forget, with bigger footprints, larger spas require more storage space during transportation, again adding to their overall price. Before buying a new hot tub carefully consider how it will be used and by who, you may be a couple without children or in retirement and are looking for some personal therapeutic use, in that case our Caldera Spa Aventine, Celio and Kauai could be the perfect fit for you. Alternatively, you could have a large family or may be a bit of a sociable butterfly entertaining a wide circle of friends. In that case our Caldera Spas Vanto, Salina or Cantabria could be the perfect choice for you with seating for 7-8 people you really are spoilt for space and comfort!

Does adding features add cost?

Caldera Spas Cantabria EcstaseatHot tubs have evolved quite considerably over the last decade and, it’s safe to say, so have our expectations! We expect a lot more from our commodities these days, smart phones now deliver our favourite films and shows on the go, we can transfer money via our tablet devices and browse the internet on our TVs and hot tubs are no exception. We all expect an incredible spa experience and most hot tubs offer a certain level of this. If you are looking to spend more money on a hot tub then you can expect more advanced, diverse hydrotherapy jets, more powerful and silent running pumps together with more intuitive control from your spas display panels and more sophisticated water care systems that help you reduce the need for hot tub chemicals. State of the art music systems, bass hungry sub woofers, multi colour change lighting and waterfalls will also add to the overall experience when using your spa, together with that overall cost.

So before you consider a purchase decide what will matter most to your spa experience. If you’re looking for a peaceful retreat from a hectic working life then the quality and variety of powerful hydrotherapy jets could be the most important consideration for you. If so, make sure you discover the Atlas Neck Massage on our Utopia series of Caldera Spas and in particular the incredible UltraMassage lounge seat on the Cantabria featuring the customisable UltraMasseuse System, the absolute pinnacle of hydrotherapy massage relief! Alternatively you may be looking to use your hot tub as an entertainment piece, so perhaps a sound system incorporating individual seat speakers and easy to use, intuitive bluetooth technology is going to be your first priority. We’re all different and will use a hot tub in our own unique ways but thankfully, with so much product diversity and unique features, our Caldera Spas offer something for everyone.

Is hot tub design really a consideration for me?

Euphoria footwell jets on the Caldera Spas Tahitian hot tubThis element is often overlooked and least considered by customers when buying a hot tub. Good design will often go un-noticed because you’ll find using a well designed, well considered hot tub effortless. Badly designed lounger seats and poorly positioned jets can cause you to float out of position when using your hot tub and having to constantly adjust yourself can create unnecessary body tension, somewhat counter productive to a hot tub delivering relaxation and stress relief! Make sure you look at the ergonomic seat design and wall structure of any potential hot tub as well, curves are more comfortable than straight sides and great design always maximises the occupant space when in use.

Other little features that make a big difference are the positions of the control panels (within arms reach is ideal) and the size of the footwell space. Regardless of how many bums on seats a manufacturer may quote on it’s glossy literature take a close look at the all important footwell space. Hot tub’s designed with a generous amount of legroom and footwell space will give you, your family and friends a much more comfortable experience when using the hot tub.

A good hot tub will offer much more than just a centre piece for your garden, it should become part of your lifestyle and fit every aspect of your daily routine perfectly. Pay close attention to the inviting colours, cabinet textures, seat and lounger shapes and interior and exterior lighting of our Caldera Spas, you’ll probably agree that they offer that little bit more.

What you should consider with performance

Caldera Spas Vacanza Series Vanto hot tub coverProbably the most difficult aspect of a hot tub purchase is considering the performance that it’s going to deliver on a day to day basis. Although many hot tubs may look similar there are many differences between low and high end spas. Although cheap hot tubs may have many jets, there could be cost savings being made underneath the cabinet with underpowered pumps providing a less intense, less satisfying hydrotherapy experience. The best hot tubs on the market are fitted with powerful, yet quiet, circulation pumps that are able to efficiently circulate the water through the hot tub filter and heater with ease.

Superior performance can also be measured in the efficiency of the cabinet insulation to help keep heat in the spa water. All Caldera Spas feature a revolutionary FibreCor technology that is four times more efficient than traditional foam insulation used on cheaper hot tubs. Perhaps the last consideration on any one’s mind when looking at a new hot tub is the base pan design. Base pan what? This is the part of the hot tub you may only see on the day of installation (when it’s delivered on it’s side) but it is always in contact with the ground, another area for heat loss. Our Utopia range features a new ABS base pan that has a corrugated design to help minimise contact with the ground and protect the components, improve energy efficiency and add support.

So ask yourself, if Caldera Spas go to so much trouble to make the parts you don’t see as well designed and efficient as possible in terms of performance, how much time do they invest in the components you do see on their hot tubs? And, perhaps more importantly, are cheaper hot tubs from other manufacturers going to deliver you the same performance.

So what next?

This guide should help you make more considered, informed buying choices when you’re buying a new hot tub and should give you a better idea of what is actually being offered at the price point you consider.

At All Swim we always recommend looking at a prospective purchase rather than just ‘buying online’ as you have the opportunity to closely examine your new hot tub and really get a feel for the quality of the build. We also offer wet tests at our hot tub showroom here in Cardiff so if you really want to discover the Caldera Spas difference we would be more than happy to see you!

Understanding water balance in your swimming pool and hot tub


All Swim stabilisedchlorine granulesWhen chlorine is added to pool or spa water a portion is consumed in the process when it destroys bacteria, algae and other contaminants introduced to the swimming pool or hot tub water. The amount of chlorine consumed is known as chlorine demand. Sunlight, bacteria, perspiration, urine, algae, make up, fake tan and many other forms of debris all create this chlorine demand.

Once this initial demand has been met, the chlorine that remains in the water is referred to as the total residual chlorine, which is a combination of free available chlorine and combined chlorine. The free available chlorine is the active chlorine that’s left to kill any new contaminants entering the pool or spa. Combined chlorine is tied up in nitrogen and ammonia compounds referred to as chloramines, which remain in the water from organic waste from swimmers and bathers. Chloramines are responsible for eye irritation and the chlorine odor that some people find offensive. When chlorine is tied up in chloramines it loses most of it’s effectiveness as a sanitiser.

To keep a swimming pool or hot tub sanitary with chlorine it is necessary to maintain the following free chlorine residuals:

  • Residential Pools between 1.0 and 3.0ppm
  • Commercial Pools between 1.5 and 2.0ppm using Calcium Hypochlorite or Liquid Chlorine, sometimes a little lower if using UV
  • Residential & Commercial Hot tubs and Spas between 3.0 and 5.0ppm

When levels are kept within this range chlorine is able to control organisms as well as destroying any new contaminants entering the pool or hot tub.

Super Chlorination

Super chlorination is recommended as a weekly treatment if temperatures exceed 90 degrees, when your swimming pool or spa is receiving a heavy bather or swimmer load, is subject to long periods of rain or when high winds carry debris and pollen into your pool. Super chlorination is the addition of an extra dose of chlorine to pool or spa water, which brings the free available chlorine levels to 3.0 to 5.0ppm (Generally a super chlorination boosts the free chlorine level up to between 5 – 10ppm). This helps restore the chlorine’s ability to control algae and bacteria. Some algae spores can also become immune to small doses of sanitisers so super chlorination can help combat this.

Shock Treatment

All Swim stabilisedchlorine granules Shock treatment is a larger dose of chlorine to bring the free available chlorine level up to 10ppm. This is intended to control visible algae, burn out organic swimmer and bather waste and destroy excess chloramines. When swimmers complain of burning eyes and a strong chlorine smell, it is due to excess chloramines and not enough free available chlorine residual in the water - not too much! The odour can also be even stronger if the pH is also low. The use of a periodic shock treatment along with a normal chlorination routine will aid in the prevention of undesirable side effects of using your swimming pool or hot tub. After shock treatment do not resume swimming or bathing until the chlorine residual drops to below 3ppm.

Please note, if your chlorine reading is very high, typically 10ppm, you may obtain a false result when testing for pH with a testing kit. In these cases lower the chlorine levels first before testing for pH and total alkalinity.


Bromine is another type of pool and hot tub sanitiser, although it is quite different to chlorine. If you using Bromine you won’t require a conditioner (an additive that helps prevent chemicals dissipating under the action of the ultraviolet rays of the sun). Like chlorine, bromine combines with nitrogen and ammonia compounds to form bromamines (as opposed to chloramines). Unlike chloramines, bromamines do not irritate eyes or have an offensive odour, and bromamines are effective sanitisers. Bromine is a more effective sanitiser at higher temperatures and therefore is a popular choice for hot tubs and with pool and spa users that dislike the unpleasant odour associated with chloramines.

A molecule of bromine is 2.25 times as heavy as chlorine, a 1.0ppm chlorine residual is therefore equivalent to a 2.25ppm bromine residual. Therefore, it is important to maintain the following bromine levels:

  • Residential & Commercial Pools between 2.0 and 4.0ppm
  • Residential Hot tubs and Spas between 3.0 and 5.0ppm
  • Commercial Hot tubs and Spas between 4.0 and 6.0ppm

When levels are kept within this range bromine is able to control organisms as well as destroying any new contaminants entering the pool and hot tub.

PH & Total Alkalinity

The two most important factors in controlling your sanitisers ability to kill bacteria are pH and total alkalinity levels.

All Swim PAK 2pH is a value expressing the relative acidity or alkalinity of swimming pool or hot tub water. It is expressed as a number from 0 to 14 with 0 being the most acidic and 14 being the most alkaline. A value of 7.0 is neutral. Low pH values cause corrosion of equipment and pool or spa surfaces. High pH values cause scale to form on equipment and on pool or hot tub surfaces. The ideal range for pools is 7.2 - 7.6 and the ideal range for hot tubs is 7.0 - 7.6. For swimming pools, to raise pH you will need to use Sodium Carbonate or PAK 2 and to lower pH you will need to use Sodium Bisulphate or Pool Acid. For hot tubs, to raise pH you will need to use Aquasparkle pH Plus and to lower pH you will need to use Aquasparkle pH Minus.  

Total Alkalinity is the ability of water to resist a change in pH. It is also commonly known as the buffering capacity of water. High alkalinity makes it hard to change the pH and may cause scale. Low alkalinity causes dramatic changes in pH, often referred to as pH bounce, and causes corrosion of equipment and pool or hot tub surfaces. The ideal total alkalinity varies depending on the type of sanitiser you are using. For swimming pools, to adjust your Total Alkalinity you will need to use Bicarbonate of Soda or PAK 1. For hot tubs you will need to use Aquasparkle TA Plus.

Always remember, total alkalinity is the key to water balance. Always adjust total alkalinity first and then adjust the pH.

Sanitiser type Ideal Total Alkalinity range

Liquid Chlorine
Calcium Hypochlorite

80 - 100ppm

Gas Chlorine
Trichlor tablets
Bromine tablets

120 - 140ppm

Dichlor granules
Two part bromine

100 - 120ppm

pH and Total Alkalinity are related. It is not possible to change one without affecting the other.

Conditioner or Stabiliser

Whatever type of chlorine chemical you use in your swimming pool or hot tub as a disinfectant is a very active chemical that is easily dissipated by the ultraviolet rays of the sun. To prolong the useful life of free, available chlorine the addition of cyanuric acid (conditioner) is recommended when filling a new pool or at the start of each swimming season if required. Conditioner acts as a type of chemical umbrella, protecting the chlorine sanitiser against loss against the sun’s UV rays. The ideal range for pool stabiliser is 30 - 50ppm. All Swim Conditioner is ideal for adjusting the levels of stabiliser in your swimming pool.

Calcium Hardness

All Swim PAK 2Calcium hardness refers to the portion of the swimming pool or hot tub water’s total hardness due to calcium salts. Calcium hardness will vary with your local water source, the chemicals you add to the water and the rate of evaporation. If you’re based in Wales you can check your local authority’s source water quality at the Welsh Water website.

High calcium hardness can cause cloudy water and also cause the formation of scale on pool and spa equipment. If hardness reaches a level of 400ppm, approximately 25% of the pool or spa water it should be drained and refilled. Soft water without hardness is undesirable because it can cause equipment corrosion and adversely affect the grout on concrete tiled pools. Recommended hardness levels are 200-400ppm for tiled pools and 175-250ppm for vinyl, fibreglass or other types of pool and spa surfaces. Increasing water hardness can be achieved with the use of All Swim’s Pak 3, Calcium Chloride.

What to look for in a hot tub

Our guide to buying hot tubs

There are a bewildering array of hot tubs and spas on the UK market and it can be confusing knowing which spa is going to be the right choice for you and your family. Thankfully All Swim have done a lot of the hard work for you. We’ve been in the swimming pool and hot tub industry for over 45 years and our hot tub expertise will help you make the right buying choice.

Choosing the right hot tub for you

Should I research hot tubs online?

The fabulous Caldera Cantabria in their Utopia series

The hot tub market in the UK is growing every year. According to Nick Clamp, owner of What Spa? magazine, feedback from retailers and manufacturers has the current UK ownership at nearly 300,000 households. Joining this growing market is certainly an exciting prospect, but do some research online and find out why people are choosing a hot tub lifestyle. What exactly is it going to offer you and your family? Decide what are the important factors in wanting an outdoor hot tub and read hot tub reviews and comments from other owners online. Researching our range of Caldera Spas will also give you a good indication of why they offer more for your money compared to other manufacturers.

Be warned though, that a great deal online may be too good to be true. It’s always better to view hot tubs or spas before you buy them. If the hot tub you’ve decided to buy online has an inferior build quality, cheap jets and pumps or sub standard cabinet and cover insulation you’ll probably end up with a spa that costs you more to run and repair than you expected. It’s also important to check that the product has official CE marking. An abbreviation of the French phrase ‘Conformité Européene’, it means ‘European Conformity’ and indicates to government officials that the product can be legally placed on a country’s market place and safeguards consumers best interests. A hot tub is likely to be a long term investment and should provide you and your family with years of entertainment, make sure you understand the quality of your preferred hot tubs by visiting a reputable hot tub showroom like All Swim.

Is how a hot tub made important?

There are many different manufacturing processes involved with building hot tubs and if there’s a difference in price, there’s likely to be a difference in the build quality. Look carefully at a hot tub retailer’s website. You should be able to find plenty of information on their products, technical specifications and warranty details. Pay particular attention to the level and type of insulation used in your hot tub, our Caldera hot tubs utilise a revolutionary new loose, wool-like fibre called FiberCor® insulation - with four times the density of traditional urethane foam (used in most hot tubs) it has vastly improved insulating efficiency and fills all voids and gaps in the hot tub compartment. With a better insulated cabinet you will be spending less time heating your hot tub water, and that translates to lower running costs which, most consumers would agree, is an important consideration for purchase. It’s also important to look at the quality of the rigid cover supplied with your hot tub. Most of the heat loss will occur on the surface of the water so a strong, full-foam insulated cover with a durable, marine grade vinyl will help you reduce your running costs. Also check the cover has skirts on all sides of the hot tub when it’s closed as this will ensure the very best thermal seal.

What size hot tub should I choose?

Hot tubs are available in many different shapes and sizes. Your first consideration should be how much space you have in your garden and how many people are likely to be using your new hot tub. If you have a big family or like having friends around regularly for parties then you will probably need a larger hot tub with multiple seating positions. Be careful though, how much access you have at your property will also be a consideration for delivering your new hot tub. Don’t worry though, All Swim offer free site surveys so if you’re unsure of anything we are happy to advise.

It may sound obvious but always try and sit in a new hot tub in a dealer’s showroom, hot tubs look very different from the outside than they do sat in them! Visiting your local hot tub showroom with family or friends will allow you to try them on for size. Pay particular attention to the size of the foot well and the ergonomic design of the seating positions. A hot tub may specify a large array of seating but if it comes with a small footwell you’re likely to be struggling to fit everyone into your new hot tub!

What is hot tub hydrotherapy?

Discover the Euphoria jet features in the Utopia range

Hydrotherapy is a term used to describe the use of water for pain relief and treating illness. Water is a great way to soothe aching joints, help relax and reduce stress levels. The design, configuration and quality of hydrotherapy jets in your hot tub is probably the most important aspect of your new hot tub purchase, you’ll want to ensure you’re getting the best possible massage for your money. Caldera hot tubs differ to any other on the market with the introduction of their unique Hot Tub Circuit Therapy. Similar to the approach used by personal trainers, a Caldera Spas hot tub treats individual muscles with strategically placed jets and purposefully designed seats throughout the hot tub itself, moving you from station to station helps deliver a full body workout and intense all over massage.

Do I need help looking after my hot tub water?

Buying a hot tub is an important decision to make but proper care and maintenance of your water can be just as important. Well maintained spa water will ensure you and your family are safe and you will help prolong the life of your hot tub. Buying cheap hot tubs online or from large high street retailers may save you money in the short term but you could be left to make costly water balance mistakes on your own. All Swim ensures you have ongoing support from our trained staff and helpful advice on correct water balance tips if you ever need them.

Our Caldera spas have also been purposefully designed with you, the end user, in mind. The integrated spa frog system takes a lot of the work out of dosing your hot tubs water correctly and the Utopia and Paradise series feature Monarch CD Ozone systems that naturally kill bacteria helping reduce the cost of chemical sanitisers.

We will always provide an informative introduction to your new hot tub with our delivery, positioning and commissioning service. Our trained spa engineers can talk you through the set up of the hot tub and answer any questions you may have on looking after the water on the day your hot tub arrives.

How important is a good hot tub cover?

Hot tub covers are key to retaining heat on your hot tub

p>Most of the heat lost from the water in your hot tub will occur from the surface so a well designed, efficient hot tub cover is a great asset. Caldera hot tub covers are designed to be energy efficient, meeting the most stringent energy standards established by the California Energy Commission for portable spas. Keeping your hot tub covered when not in use will not only ensure you spend less money heating the water but it will also prevent airborne debris entering the hot tub water and adversely affecting the water quality.

Can I play music in my hot tub?

Absolutely! If music is an important aspect of your hot tub lifestyle then our Caldera Spas won’t disappoint. Almost all models across the Utopia, Paradise and Vacanza ranges are available with a fantastic bluetooth enabled music system, a few clicks and your smart phone, tablet or laptop can be synchronised effortlessly with your hot tub.

Can I spread the costs of a hot tub purchase?

Yes you can. All Swim have always put the customer first and our finance packages will help you spread the payment costs and ensure you find an affordable hot tub to suit you and your family’s budget. We can offer 12 and 24 months interest free credit at 0% APR or a 60 month finance option at 4.9% APR. You can even apply for finance online today!

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