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What chemicals do I need for a hot tub? (Guide, helpful tips and more)

July 7, 2023

Estimated read time - 6.5 minutes

Author – Fin Green – Content Creator UK, Jacuzzi Group 

Do you own a hot tub and are not sure whether you’re using your chemicals properly? Are you considering buying a hot tub and wondering which chemicals to put into it?  

We're here to help! Read our basic guide to understanding the most common hot tub chemicals and how to use them.

By the end of this article, you will have an idea of the most used chemicals are in hot tubs, what they are used for and why they are an important part of the hot tub maintenance process.  

What chemicals do I need for a hot tub? Guide, helpful tips and more

Please note - Each hot tub has its own chemical needs and this a general guide with tips from experts within Jacuzzi Group that is not specific to one hot tub brand or model. To find a guide that’s specific to your hot tub, contact your brand or dealer for advice for the information you need.

Why does my hot tub need chemicals?  

Bacteria thrives in warm environments and yes, this can include within hot tubs, if the water is left untreated and chemical and maintenance instructions are ignored.  

A warm environment, as well as rainwater, outdoor temperatures and bodily oils will make your chemical balance change constantly. This means chemicals need to be added to regularly strike the right balance again to keep the water clean and healthy to soak in. 

What is chemical balance in a hot tub?  

Ever heard people say they need to ‘balance the water’ in their hot tub? Chemical balance in a hot tub is all about making the water clean, safe and comfortable to use.

You can achieve this with the help of several chemicals and products – sanitiser, pH balance and calcium hardness. The products used will vary between brands and models and it is always best to follow instructions and recommendations from hot tub experts and sales teams.  

What chemicals do I need for a hot tub? 

Hot tub sanitisers  

Let's start with looking at the chemicals that you use to get rid of the bacteria, the sanitisers. Did you know, there are only three chemicals that are considered hot tub sanitisers:  

  • Chlorine - The most popular hot tub sanitiser is chlorine. A sanitiser you will be very familiar with if you have spent any time around pools.  

  • Bromine - Bromine is good for those who like sitting at a higher temperature s it can stay at a stable temperature even when the heat is up.  

  • Oxygen - Oxygen is an effective, natural sanitiser for your skin. That’s because your body is already familiar with it. However, it is required in a combination of both liquid and tablets to be an effective sanitiser for hot tubs.  

The common metric unit used for sanitisers and most chemicals is ppm (part per million). This is the same as mg/l (milligrams per litre).   

Sanitisers and various chemicals are typically quantified with the metric unit of ppm (parts per million). This is equivalent to mg/l (milligrams per litre). 

Clean hot tub water

What chemicals come in a hot tub chemical starter kit? 

Products in a starter kit will vary, depending on what brand of hot tub you're buying, where you're buying them from and what sanitiser option you have chosen.

As an example of what Jacuzzi® offers, you can choose between chlorine granules and bromine granules. The kit also includes 50 Jacuzzi® Test Strips, 500G Jacuzzi® PH+, 500G Jacuzzi® PH-, 500ML Jacuzzi® No Foam, as well as a Jacuzzi® Hot Tub Chemical Guide. 

Hot tub chemicals  

There are many other chemicals that play a role in keeping your hot tub water balanced and ready to go.


  • Test strips – You will need to test the chemical balance of your water. Test strips can determine the PH balance, alkalinity and sanitiser levels so you can add chemicals accordingly.  

  • Shock treatmentsCommonly used in swimming pools, shock treatments can kill bacteria, remove contaminants and reactivate sanitisers.  

  • No Scale – Needed in hard water areas to stop solidified scaling and calcium building up.  

  • Calcium Hardness Increaser – Boosts calcium levels in regions with low water hardness. 

Click now to find the majority of these products and more in the maintenance section of Jacuzzi® Shop.  

Using test strips for a hot tub

What is total alkalinity?  

Total alkalinity (TA) measures the amount of alkaline in your hot tub water. The ideal level of alkalinity is between 80-120mg. You can strike the right balance by using alkalinity increaser. This will raise the TA level or a pH decreaser to lower the TA level.  

Why is TA important?  

If the alkalinity level is too high or too low, then it can affect your pH balance. It is important to keep alkalinity levels balanced as possible.  

What is total hardness?  

Have you ever noticed scale and limestone build up on your water taps and pipes? That is because the total hardness (TH) is too high. Total hardness refers to the amount of calcium and magnesium mineral content in your water.  

If your TH is too high, you can use a ‘no scale’ product to bring levels down and use a Calcium hardness increaser if your TH level is too low.  

Why is TH important?   

You must measure the total hardness of your water and make sure it is between 100-250ppm, otherwise calcium may solidify in your hot tubs surface and internal parts.  

Why is chemical balance important in my hot tub?  

You may now be thinking, well that’s a bit excessive? This section is to tell you exactly why each chemical your specific product needs is detrimental to your health, and your hot tubs.  

pH hot tub level – What does this mean?  

You may remember from school that pH is a measurement between 0-14 which determines the of the acidity and alkalinity of your water.  

A measurement of 7 is the number that will mean that your hot tub is perfectly balanced, using pH increaser or pH decreaser to reach magic number 7.  

Why is pH important?

A measurement lower than 7.2 means that your water is too acidic and can cause eye burn and itching. A measurement above 7.8 means that your water is too alkaline and is therefore vulnerable to scale build up.  

Clean hot tub in garden

Can I use pool chemicals in a hot tub?  

The short answer is no, it is not advised or recommended to put swimming pool chemicals into a hot tub.  

Swimming pools chemicals are designed for low temperature water. They are less concentrated to match the cooler temperature a swimming pool is typically set to.  

Hot tub chemicals are designed for water set to a higher temperature and have a higher level of concentration.  

If you were to add pool chemicals in a hot tub, you will notice that it will burn off quickly.  

That’s because low-level concentrated pool chemicals are not designed to withstand the warm temperature of your hot tub and the higher concentrated level that’s needed to have an effective impact on keeping your hot tub water clean and healthy.  

What is trichlor?  

Trichlor, also known as trichloroethylene, is a chemical compound and a pesticide that’s EPA (Envrionmental Protection Agency) registered.

It acts as a disinfectant and sanitiser by releasing chlorine into the water. That’s why it is commonly used to treat water in swimming pools. We advise against using this particular chlorine type for hot tubs due to its high acidity and slow dissolving properties.  

Prolonged exposure of trichlor to the spa shell can lead to fading and potential permanent marking on the hot tub shell which could leave a visible line at the water level.  

What makes a high-quality hot tub chemical?  

As with most things, if something is a higher price, it is usually because the quality goes hand in hand with it.  

This is not something you should it risk when it comes to purchasing chemicals as there are different standards of chemicals, the higher priced ones usually have higher grade chemistry.  

If the chemicals aren't of a high standard, then they can affect the efficiency of your hot tub, as well as be uncomfortable to sit in.  

Some elements within chemicals can be extremely damaging to hot tubs inner and outer parts.  


Hopefully you now know the basics of hot tub chemical maintenance. Please be aware that this article only covers a general overview of UK hot tub chemicals and their average dosage and levels.  

Yes, there are several chemicals and extras that are needed to maintain your hot tub water, but when they enable you to soak in clean, healthy water, it's worth it!

To browse for products or refills you may need, head to the maintenance section of Jacuzzi® Shop. 

If you have some chemical maintenance questions that are specific to Jacuzzi® Hot Tubs, click the View Showrooms button to locate the one nearest to you.

By picking up the phone or visiting in store, our teams will be more than happy to answer any questions you may have.