Hot tubs require a wide range of chemicals to be kept in top working order. Understanding all of these hot tub chemicals can be very difficult, particularly if you are new to the world of hot tubs. In this hot tub chemicals guide, we will explore the different kinds of chemicals that you’ll need to use in your hot tub, going into detail about what each chemical does and why they are necessary.

If you’re ready to learn more about different chemicals that your hot tub needs and what they all do, then read on and let’s get started!

Always Test Your Water

Keeping your hot tub water within a healthy pH is very important. We have previously explored hot tub pH balance in greater depth, but in essence, pH is a measurement of how acidic or basic a substance is. A measurement of below 7 indicates an acidic solution, while above 7 indicates a basic solution.

Your hot tub water should always be kept between 7.4 and 7.6 pH. Straying too far from this pH level could result in irritation to the skin or eyes, as well as other unpleasant side effects. Testing your hot tub’s water is easy – all you will need are pH testing strips, which you immerse in your hot tub’s water and observe what colour the testing strip changes to, then use a chart to see what pH level the colour represents. However, if you want a more precise measurement, you can also use a water testing kit. 

As many of the hot tub chemicals you’ll use regularly will be either acidic or alkaline, regularly testing your water is essential.

Hot Tub Sanitisers

The most well-known, but also perhaps the most important, type of hot tub chemical is sanitisers. These hot tub chemicals are required to keep your hot tub clean and free of bacteria. No matter how clean you may be, bacteria will enter the water on your skin, your clothes, and the air around your hot tub. This is by no means an exhaustive list of all bacterial vectors.

For this reason, using hot tub sanitisers is of the utmost importance to keep your hot tub in good working order. Dirty water, infested with bacteria, can lead to skin infections or illnesses such as Legionnaire’s Disease – not to mention the fact that too many bacteria can make your hot tub’s water green, cloudy, or allow for algal growth. How often you’ll need to add sanitiser will depend on your hot tub model, so you should test your hot tub water daily and top up as necessary.

Your Sanitiser Options

When it comes to choosing a sanitiser, you will have two main options available to you. One is chlorine, which you’re probably familiar with from public swimming pools, while the other is bromine.

In this section, we will explore how they both work and the advantages and disadvantages of each. You can explore our blog post bromine and chlorine for a more in-depth explanation.

Using Chlorine in Your Hot Tub

One of the most popular sanitisers on the market is chlorine. Usually sold as granules, chlorine is a strong oxidising agent that will destroy bacteria by oxidising it. Perhaps the biggest advantage of chlorine is that it’s typically cheaper than bromine, and is also widely available in most hot tub shops. It also works faster than bromine, which could be ideal if you need to quickly sanitise your hot tub before use.

The chief downside of using chlorine as a sanitiser is that it tends to create smelly chemicals called chloramines. You might be familiar with these smells from swimming pools – they’re created when chlorine oxidises things like oils from your skin or flakes of skin. These can, ultimately, result in breathing difficulties if there are too many of them. Chlorine can also cause skin irritation, called irritant contact dermatitis.

Using Bromine in Your Hot Tub

Bromine is a less commonly used but still popular alternative to chlorine. Bromine is also sold as granules, and should not be too difficult to find if you decide to use it in your hot tub. Bromine is also an oxidiser like chlorine, which means it’s fully capable of keeping your hot tub clean and safe.

Bromine tends to be a gentler alternative to chlorine, which makes it an ideal choice for those with sensitive skin. It also lasts longer than chlorine and won’t produce chloramines, although it does produce a less smelly class of chemicals called bromamines.

Bromine also requires fewer applications than chlorine, but it can also be deactivated by sunlight. If you decide to use bromine in your hot tub, you should keep your hot tub covered to make the most of your sanitiser. 

Hot Tub Shock

Another type of chemical that should be in every hot tub owner’s toolkit is hot tub shock. Hot tub shock is, like sanitiser, made up of oxidising agents, either chlorine or bromine. The key difference is that when you shock a hot tub, you use a significantly higher dose of either chlorine or bromine. You should use hot tub shock in your hot tub at least once per week – regular shocking is required to keep your hot tub clean, in addition to your regular sanitiser.

Non-chlorine shock is ideal, as it will remove any chloramines that could be making your hot tub smell. 

What Kind of Shock Should I Use?

It’s okay to use chlorine shock in a hot tub, whether you use chlorine or bromine as your sanitiser. It also tends to be stronger than non-chlorine shock. You may wish to use chlorine shock every two weeks to ensure algal growth is kept in check, and use non-chlorine shock the rest of the time. It’s important to note that you should never mix chlorine and bromine while they’re both dry, as this can lead to potentially lethal chemical reactions.

Chemicals to Balance Hot Tub pH

As we previously mentioned, keeping your hot tub’s pH balanced is of the utmost importance. If your water’s pH levels are too high or too low, it can cause problems ranging from cloudy water to irritated skin, and can even damage the hot tub. Sanitisers can affect the pH of the water, but if you’re regularly sanitising your hot tub and your pH levels are still unbalanced, you will need to use chemicals that increase or decrease the pH level.

You should have chemicals to both increase and decrease your hot tub’s pH levels in your toolkit.

Both of these chemicals are sodium compounds. They are, specifically:

  1. Sodium bisulphate, an acid salt, as your pH reducer.
  2. Sodium carbonate, as your pH increaser.

Water Hardener

While soft water is better for drinking (and using it in your kettle), it can cause serious issues for hot tubs. Soft water can corrode the shiny fixtures of your hot tub, and it can also make your spa foam up more than it should. For these reasons, you should ensure that you have a water hardness increaser.

This chemical is typically calcium chloride. You should add it as required and can test your water hardness with testing strips. If you notice that your water has become too hard, you can drain some of the water and add fresh water to your hot tub.

Water that is too hard can also cause issues, including calcium build-up. If you have hard water, staying on top of your hot tub maintenance checklist is essential, and you can also purchase scale inhibitors to prevent the build-up of limescale.

Hot Tub Pipe Cleaner

Cleaning your hot tub is an involved process, and a vital one at that. You probably already know that you need to clean the hot tub’s chassis and its filters, but you need to clean the pipes, too. So, how can you do that? That’s where a hot tub pipe cleaner comes in.

These are strong chemicals that you apply to the water before turning on the hot tub’s pump (with air controls closed) and let circulate. Once they’ve circulated, you’ll then need to drain your hot tub and refill it.

Cleaning the plumbing lines in your hot tub is vital because minerals, grime and more can accumulate inside the pipes. Left uncleaned, these could potentially cause issues with water flow, and can even cause clogs.

Hot Tub Chemicals: Essential Tips

We’ve covered the key hot tub chemicals that you need to keep in your toolkit. In this section, we’ll highlight some essential tips that you should know when using them. Hot tub chemicals are often very powerful and can be dangerous if used improperly.

Safely Adding Chemicals

When adding chemicals to your hot tub, you should only ever add one at a time – mixing chemicals can cause significant issues. When adding them, add them directly to the water and then wait at least 20 minutes before you add any more. A longer waiting period may be required for some chemicals, so always read the packaging carefully.

Do Not Keep the Cover On

You should always keep the cover off of your hot tub when you’re adding chemicals. There are two key reasons for this. Firstly, the chemicals could damage your cover, and secondly, some chemicals will release gases while doing their job, which you should allow to vent into the open air.

Handle Chemicals Safely

When handling hot tub chemicals, it is of the utmost importance that you stay safe. Always read the packaging on your hot tub chemicals and follow the instructions to ensure safe usage.

Use Our Hot Tub Chemicals Guide to Keep Your Hot Tub Clean and Safe

We hope that you have found our guide to hot tub chemicals useful. While the wide array of chemicals that you need to use in your hot tub can be intimidating, we hope that you now have a good understanding of what you need to use and why. 

If you do not yet own a hot tub and would be interested in learning more about our various models, please contact us today. Our expert team will be happy to assist you.

Hot Tub Chemicals FAQs

While all of these chemicals are important, sanitiser is perhaps the most important. Chlorine or bromine is vital to keep your hot tub water safe to use.

Before using your hot tub chemicals for the first time, allow your hot tub to heat up to a temperature of 27 degrees Celsius. This will help the chemicals to dissolve in the water.

Yes, the chlorine levels in your hot tub can be too high. If you are worried about this, we recommend testing your water with pH strips to ensure that your chlorine levels are safe.

Sarah Watkins