Borax In Hot Tub Maintenance: What It Is & How to Use It

Jennifer Rhodes

By Jennifer Rhodes · Updated

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Though you may think of borax as that classic cleaning material in your grandparents' kitchen cupboard, this chemical compound actually has significant benefits when added to hot tub water. But what is borax and how do you use it?

Borax is a chemical formula that acts as a pH buffer and water softener. Adding it to your water can help you limit the amount of chlorine or other chemicals you need to keep your hot tub water sanitized and algae-free. Additionally, it makes your water less harsh on your skin, as well as sparkling clean.

In this article, we'll explain what borax is in more detail—and how to use this handy chemical in hot tub maintenance.

What is borax?

Borax is a powdery white salt that contains a formula helpful for maintaining safe chemical levels in a swimming pool or hot tub. Usually, it contains borate, the chemical it is named after, and some additional chemicals that add extra benefits to your hot tub. The compound is added to spa water for two main reasons:

  • Acts as a pH buffer, keeping the pH level in your spa more consistent
  • Can raise pH levels without affecting the Total Alkalinity (desirable when TA is already in range)

Borax also has additional benefits for your hot tub water. For example, it softens your water, preventing corrosion and metal stains, and giving it a silky feel. It can even function as an algaecide.

How do I use borax in my hot tub?

There are three commonly used sources of borates: 20 Mule Team Borax, Boric Acid, and ProTeam's Gentle Spa. However, it's important to note that only borax significantly raises pH levels.

This is great if that's what you want, but if you are mostly looking for the other benefits, you will need to add acid (like muriatic acid or another pH down product) to balance it and bring the pH back into range.

For a more balanced approach without the need to counteract a substantial pH increase, I'd opt for Boric Acid or ProTeam's Gentle Spa. Both of these options will yield the same results.

Proteam Spa Gentle Spa (2 lb) (2 Pack)
Proteam Spa Gentle Spa (2 lb) (2 Pack)
View on Amazon

The correct dosage will vary depending on the product you're using, the size of your spa, and the other levels. The easiest way to figure this out that I've found is to use the Pool Calculator. This will let you put in all the relevant values and calculate the right amount for you.

How do I measure borate levels in my hot tub?

To maintain a stable pH level in your tub and create a softer water feel, it's recommended to maintain approximately 50 ppm of borates.

To test the level, you can get test strips—just like you are probably used to from testing your other levels! Beware though, borates are usually not tested by regular combined test strips which you might already have. If that's the case, you'll need to grab some specific borate testing strips like these:

NEW AQUACHEK 562012 Pro Swimming Pool Spa Hot Tub Borate Water Test Strips
NEW AQUACHEK 562012 Pro Swimming Pool Spa Hot Tub Borate Water Test Strips
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Is borax safe?

Compared to some other chemicals used in spa maintenance, borax is one of the safest around. The Environmental Protection Agency state that the substance isn't toxic to humans in low doses. It doesn't irritate the skin on contact either, which is one of the reasons why it's so great for hot tub water.

Even with this information, borax still isn't the safest thing to have around in your home. If you're exposed to too much dust, this can cause respiratory irritation, which is particularly common in children. Also, it's not meant to be consumed—if a large amount is ingested, it can cause vomiting, diarrhea, and nausea.

So, just like with all other chemicals for your hot tub, be sure to always store borax in a safe place out of reach of children.

Are there any downsides to using borax in my hot tub?

With any chemical, there is the potential for issues. Here are a few things that you can run into when using borax:

  • pH Increase: Borax tends to raise the pH level of your hot tub water. This means you may need to monitor and adjust the pH more frequently to maintain the desired balance. If the pH level becomes too high, it can lead to issues like cloudy water and scale formation.
  • Potential for Alkalinity Increase: Along with raising pH, borax can also increase total alkalinity in your hot tub. High alkalinity can make it challenging to maintain pH stability and may require additional adjustments.
  • Limited as a Sanitizer: Borax is not a sanitizer or disinfectant itself. It won't effectively kill bacteria or other microorganisms in your hot tub water. You'll still need to use an appropriate sanitizer, like bromine or chlorine, to ensure water safety.
  • Potential for Cloudy Water: If not used correctly, borax can sometimes cause cloudiness in the water. Overdosing or improper mixing can lead to this issue.

To minimize the downsides of using borax in your hot tub, it's essential to use it sparingly and carefully, following recommended guidelines for dosage and monitoring your water chemistry regularly.

Additionally, consider alternative products like boric acid or specialty hot tub chemicals like ProTeam's Gentle Spa which I mentioned above, that can help stabilize pH without causing as many potential issues.

Weighing the pros and cons, most people find adding borax (or borates, at least) to their spa seems like a no-brainer. Though it may be a bit of a balancing act at the beginning, the long-term benefits are well worth the investment.


Though the pH balance may be hard to achieve the first time around, borax is a useful substance to add to your hot tub water. It will help save you maintenance time with its balancing effect, and make for a more pleasant bathing experience. Despite the initial extra upfront cost, most spa owners find it a beneficial addition.

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