What is hot tub pH?

By Jon Filson

Hydropool Hot Tubs and Swim Spas

Once you get a hot tub, learning how to keep your water balanced is crucial. There’s a little bit of work to do each week to ensure your hot tub is functioning the way it should and that your water is balanced.

One of the elements that must remain in balance is pH. pH literally means “potential of hydrogen” or “power of hydrogen” which is interesting but mostly useless information for most of us who just want to use a hot tub. More hydrogen leads to lower pH, which makes your water more acidic. Less hydrogen leads to higher pH, which makes it more basic.

So on a practical level, what pH levels show you is how basic or acidic your water is. Your hot tub water needs to remain in a certain range or there is risk to you as a bather in the form of skin or eye irritation or your equipment or both.

pH is one of the first things we teach new owners about and it’s one of the things we get asked about in the first few weeks after people buy their hot tubs. So we wanted to write an article that explained it in full.

So in this article, we will discuss:

  • How do you maintain pH?
  • Why do I need to maintain pH at a stable level?
  • What is low pH level? What causes low pH? How do I deal with it?  
  • What does a high pH mean? What causes high pH? How do you deal with high pH?

Once you’re through the article, we hope you know just how to manage your hot tub. Or if you haven’t bought yet, you’ll know what you have in store for you when it comes to managing hot tub pH.



How do you maintain hot tub pH?

The recommended pH range for hot tubs is between 7.2 and 7.8. In order to maintain the ideal range, you will need to frequently check the level with test strips or a kit. We recommend that you check once or twice per week and more so if you use your hot tub often.

Why do I need to maintain pH?

Why is the pH level so important? Proper water chemistry is what keeps your hot tub clean, running well and safe to use. The proper pH range is necessary for the other chemicals to be able to work as they are designed to. For example, if your level was just slightly higher at 8.2, the effectiveness of chlorine being used would drop to just 15 per cent.

Low pH is acidic, while a high pH is basic.

  • Vinegar and lemon are acidic. If your water is too acidic, over time it will eat away at your equipment and your hot tub parts making them not last as long.
  • Bleach and soapy water are basic liquids. If your water becomes too basic, your sanitizer becomes ineffective and over time calcium build up will occur.  

You don’t want either to happen. That’s why pH balance is important.

Out of balance pH: What happens with a low pH Level?

If the pH level in your hot tub is low, this will mean that your water is acidic.

  • This can cause the corrosion of your hot tub’s surface and components such as filters, water pumps, the heater and more.
  • With a low pH level, your ability to properly control the total alkalinity level is also impacted.
  • Bathers may also feel uncomfortable, experiencing skin or eye irritability as acidic water strips their skin of its natural oils, leaving it feeling itchy and dry.

Why does this happen?

  • A common cause for a pH level that is too low can be from adding too much pH reducer if you were recently trying to lower your hot tub’s pH level.
  • Another contributing factor can be using a local water source with low pH.
  • Hot tub usage can also influence the pH level. When people use a hot tub, body oil, sweat, lotions or sunscreen can enter the water. Grass, dust and even insects can also be accidentally tracked into the hot tub by bathers. These contaminants can also affect the pH level and cause it to drop.

Here’s what to do about it. There are two ways that the pH level in your water can be increased.

  • First, you can try adding new water. Often, water coming from a garden hose has higher alkalinity which can boost your pH level (your local retailer will be able to give you advice on the water quality in your area).
  • Secondly, you can use a pH increaser product. Just be sure to properly calculate the amount of water in your hot tub so that you add the correct amount. It’s best to go slow with an pH increaser as it can take time to have an effect. Try a little bit, wait, and then try a little more, rather than trying to make something happen quickly.


A well-balanced pH level is part of keeping your water sanitized and safe for use in your hot tub. The hot tub shown here is part of the Hydropool Serenity collection.


Our of balance pH: What do to do with a high pH level?

A high pH level means that your water is ‘basic,’

  • If left unattended over time the water will scale on your jets, pipes, filters and other components. Water scale also puts additional strain on your components as it reduces the water circulation and increases pressure.

There are two common reasons as to why your water pH level may be high.

  • Often, people accidentally add too much pH increaser when they are trying to correct a low pH level.
  • The other reason is that your local water source may naturally have a higher than normal level.

To decrease the pH level in your hot tub, there are two chemicals that are commonly used, dry acid and muriatic acid. Both will be sold as “pH decreaser.”

Although they both deliver a similar result, they need to be applied differently, so make sure you are aware of which one you are using and that you follow the specific instructions.

Remember, whenever you’re attempting to change pH, go slow. Try a little bit, then wait a few hours, then check again before adding more increaser or decreaser.

What is pH in my hot tub and why does it matter?

Every hot tub owner becomes comfortable managing pH in their hot tub. pH is a measure of potential hydrogen and really what it is tracking is either how acidic or how basic your water is. Let it swing too far out of whack on either side and you’ll have either immediate or long-term issues.

Fortunately, keeping your pH in line isn’t difficult. Checking your water once a week is usually sufficient as it is normally one of the most stable parts of your hot tub’s water. When it does swing up or down, there are easy treatments to adjust it back to a place that will be comfortable for anyone using the hot tub.

We hope this guide to pH has been helpful for you! If you have any further questions, don’t hesitate to reach out to us by contacting a local dealer.

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