The Perfect Balance for your Hot Tub



Balancing Chemicals in your Hot Tub is key to clean, crystal clear and problem free water. In this blog post we are going to look at what a balanced set of chemicals look like and how we can resolve some common problems.

Before we start, I must point out that this is written from personal experience, I am not affiliated to BISHTA. BISHTA is the trade association that represents the British and Irish Hot Tub and Swim Spa Industry. Nor am I professionally chemically trained. The is advice only from personal experience so please do with it what you will at your own peril!

Why do we need Chemicals in a Hot Tub?

We need chemicals in a hot tub primarily to kill bacteria that could breed in a warm damp environment. By using a combination of chemicals we are able to remove the bacteria which could be harmful to us from our Hot Tubs and control the water for longer.

What Chemicals do I need for my Hot Tub?

When we are talking about Hot Tub chemicals, we are really talking about 6 things

  • Sanitiser
  • pH Increaser
  • pH Decreaser
  • Total Alkalinity Increaser
  • Anti Foam
  • Clarifier (optional)

Let’s have a look at what each of them does.


Sanitiser is the main chemical that is going to kill bacteria in your Hot Tub. There are two main choices here. You can either opt for Bromine or you can choose Chlorine. I am going to write an article at some point about the difference and pros and cons between the two, but for this article, I am going to concentrate on Chlorine as that is what I use in my own tub and it is more popular.

Just as a side note, Bromine is particularly good if you have sensitive skin or react to Chlorine. It means you can still enjoy the Hot Tub without the associated skin complaints!

pH Increaser & pH Decreaser

Before we look at increasing or decreasing pH levels, what is pH? pH is the measurement of the acidity or alkalinity of the water in your hot tub. It is a scale from 0-14 with regular water being ‘neutral’ and as you would expect, coming in at the middle of the scale as a 7. The more acidic your Hot Tub water is, the lower the pH value. The more alkalis your Hot Tub is, the higher the value.


Why is this important? Firstly, if the water is too acidic, it is going to corrode your Hot Tub parts which is going to be costly in the long run. If you are going to corrode the heater element in the Spa Pack, this is going to cost £200-300 ($400-500). If there is not enough acidity, the water could cause stains in your Hot Tub due to mineral scaling. It can also cause health problems so it is kind of important to get it right.

One of the main things that the pH determines his how well the sanitiser works. For the ideal setup, your Hot Tub needs to between a pH of 7.2-7.6

Total Alkalinity Increaser

This is where things can get a little confusing. What Total Alkalinity (TA) is really the overall position of the alkalinity of the water. This also affect the hardness of the water. Why is this important. Well, if you cannot stabilise the TA of the Hot Tub then you will find it difficult to move the pH of the water up or down to balance. If your Hot Tub is out of balance, then the sanitiser doesn’t work effectively, bacteria and the nasties start. So it is important.

One of the things I didn’t realise was that you tent to buy TA Plus (total alkalinity increaser) but you dont buy “TA Down”. It’s a bit confusing and we will cover the scenarios further into this article. However, if you need to reduce the TA of the Hot Tub which should be at 80-120 ppm (parts per million you use pH reducer to bring it down, then you take just the pH back up to the correct level with pH Increaser. Complicated? It’s not really, just read the paragraph again if you are still not quite sure.

Anti Foam (optional)

Anti Foam is also an optional Chemical but it is one that I use. Have you ever seen a Hot Tub that is full of foam on the top? The foam is caused by detergent usually coming from the clothes of the bathers in the Tub. If the Hot Tub chemistry is not quite balanced, then the detergent can react with the water and cause excess foam.

What Anti Foam does in a simplistic way is kind of like when you put a bar of soap in a bath full of bubbles, the bubbles disappear. This is the job of Anti-Foam does.

This should be however a short term fix to the ‘problem’ which is more than likely chemicals slightly out of balance. We’ll look at this later in this post.

Clarifier (optional)

Water Clarifier. This I have marked as optional as it is not really needed but it makes the water look good. If your water has a bit of a murkiness to it because there is small drops of matter suspended in the water, this can help. What Clarifier does is that it helps the particles of matter combine into larger particles that your filter can then trap and keep out of your water.

If the particles are too small, they will pass through the filter and can cause your water to not look that appealing. Add some clarifier whilst the jets are going, a good squirt usually does it and you will soon see the gleaming sparkly incising water once again.

What is the Perfect “Balance” of Chemicals in my Hot Tub?

According to the experts the chemicals should sit between the following readings that I have summarised in an Infographic;



Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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