Do I need to use chemicals in my hot tub?

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How much maintenance does a hot tub need?

Your dream of owning a hot tub probably doesn’t involve needing a degree in chemistry. You want to buy a hot tub to relax, not to add more to your list of chores. 

So it’s no surprise that low or no maintenance hot tubs are becoming increasingly popular. As are the elusive “self cleaning” hot tubs. 

Understanding how much maintenance is needed BEFORE you buy a hot tub is a good idea. That’s not to say they need loads. But the bottom line is that all hot tubs DO need ongoing maintenance and chemicals. 

In this blog we look at why you need to use chemicals, what chemicals you need to use and how you test them. 

Related content:

➡️ Should I buy a self cleaning hot tub or swim spa?

Do I need to use chemicals in my hot tub?

As I’ve already alluded to…YES! All hot tub, swim spas and swimming pools require chemicals .

There is no way to avoid using chemicals in your hot tub. There are ways to reduce the usage. But if you buy a hot tub you will need to accept that you will have to use chemicals. And testing and dosing these chemicals will be something that you will need to become comfortable with. 

Why do I need to use hot tub chemicals?

Coast Spas filterHot tubs sit at 37-40 degrees. The perfect temperature and environment for bacteria to multiply. 

A good filtration system is the foundation of clean hot tub water. No amount of chemicals will make up for poor filtration. But no matter how good your filtration is. Nothing will stop dirt and bacteria coming into your hot tub. Whether it is blown in by the wind. Or comes from the bodies bathing in it. Dirt and bacteria are going to make it into your hot tub water.

Which means that hot tubs are a haven for bacteria. And without the use of chemicals to kill off the bacteria, your hot tub can become a playground for water borne bacteria. 

What chemicals do I need to use in my hot tub?

Your hot tub does need chemicals but it doesn’t have to be complicated. 

There are two things that you 100% need to use:

➡️ pH controller (pH plu sand pH minus)

➡️ Sanitiser (Chlorine or Bromine)

These are required to control the water and kill bacteria. They are non-negotiable. On top of those you will need to use some speciality products to deal with specific issues such as filter cleaner, total alkalinity and calcium. 

How much do hot tub chemicals cost?

Not only does adding chemicals add to your list of things to do. It does add to the overall running costs of your hot tub.

As you’ll find out below there are two important chemicals components to chemicals: controlling the pH and killing the bacteria. These are non-negotiable. 

You will also then need chemicals to help with cleaning. Below shows the average costs. How long these last will depend on how often you use it. But as a guideline a 1kg tub of Chlorine last the average house hold 6 months +. 

Most companies will give you a chemical supply with the hot tub, this usually last around 3 months. 

Chemical Approx. Cost
pH plus £10.62 for 1kg
pH minus £13.50 for 1.5kg
Chlorine £19.26 for 1kg of granules
Bromine £31.80 for 1kg of tablets
Test strips £11.94 for 50 strips
Filter cleaner £16.26 for 500ml

What do all my hot tub chemicals do?

So we know why chemicals are necessary. We need them to keep the water lean and safe to use.

But what do all the different chemicals do?

What does a pH controller do?

The ph of your hot tub should sit somewhere between 7.2 and 7.8. There are two reasons that keeping a balanced pH is important.

The first is that it’s really uncomfortable to sit in water with an unbalanced pH. It will either be too acidic or too alkaline and neither are nice to our skin. Many people think they are allergic to Chlorine, but they are actually just sitting in water with a pH that is too high or too low. So we want to keep the pH neutral so our skin and eyes are not irritated.

The second important reason pH needs to be balanced is that an unbalanced pH can make the sanitiser ineffective. So the pH needs to be held neutral so that the sanitiser can kill the bacteria. 

Related content:

➡️ How to test the pH of your hot tub water

➡️How easy is it to keep your hot tub water clean? The importance of pH

What to do if pH is wrong


Too low? (under 7.2): Add pH plus

Too high? (over 7.6): Add pH minus

Why is hot tub sanitiser do?

Sanitiser is really important as it is what kills the bacteria. While the pH creates the conditions to allow the sanitiser to do its job. The sanitiser is the one actually doing the work. 

There are two common sanitisers in hot tubs:

1. Chlorine

2. Bromine

Both essentially do the same job. Chlorine tends to be more popular as it’s slightly cheaper and more people are familiar with it. 

Bromine is popular with people who are sensitive to Chlorine. It can also be more effective in unstable pH environments so is often used in holiday homes where it is really important to have a constant supply of effective sanitiser. 

Related content:

➡️How easy is it to keep my hot tub clean? How to test hot tub Chlorine

What to do if the sanitiser level is wrong


Too high? Let it reduce naturally (if you need to do it quickly you can use Chlorine reducer)

Too low? Add Chlorine/Bromine

Do I need hot tub chemicals if I have a self cleaning hot tub?

You might have seen that I mentioned self-cleaning hot tubs at the start. They are becoming very popular with people looking to reduce chemical usage. 

So, If you buy a self cleaning hot tub, do you still need to use chemicals?

All hot tubs are technically self-cleaning. They all have filtration and circulation systems. But selling a hot tub with a filter and telling you it’s self-cleaning is like selling you a house with a hoover and telling you it cleans itself.

So yes, they all need chemicals. Even the self-cleaning ones.

Hot tubs that are sold as “self-cleaning” usually have a built in sanitiser dispenser. This will reduce the manual addition of chlorine of Bromine. But the testing, and the addition of all the other chemicals will remain the same.

There is no way around testing and dosing of hot tub chemicals bar paying someone to do it.

In summary

So do you need chemicals for your hot tub.


Chemicals are always necessary for your hot tub. There is no way around it to keep the water safe and comfortable. So if you don’t fancy using chemicals then a hot tub may not be the right choice for you. 

If you don’t fancy doing it yourself you can always pay for regular ongoing maintenance to your hot tub which will include checking the chemicals.

Related content:

➡️ How often do I need to empty my hot tub water?

➡️The best hot tub manufacturers in the world 

➡️Hot tubs Scotland: The best hot tub suppliers


Debbie Ekins
Debbie Ekins
Eagle Leisure - Sales & Marketing Manager Mission = to arm you with the knowledge you need to make the best buying decisions. Fuelled by coffee (and naps). Explorer of Scotland and the world.
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