Borax in Pools: A Complete Beginners Guide

Why would you use a household cleaner like borax in a pool?

In this article, we’ll cover everything you need to know about using borax in a swimming pool, including what it is, when it should be used, and how to use it the right way.

Quick answer: Borax is a powdery substance that has multiple applications in a pool, including raising the pH level, improving the feel and shine of the water, and even acting as a mild algaecide.

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What is Borax?

Borax, or sodium borate, is a chemical substance that’s used to raise the pH level in your pool, making the water more basic (or alkaline).

This is useful when your pH has fallen below the ideal range, whether it’s due to excessive rainwater, a sudden influx of contaminants, or the use of acidic pool chemicals such as chlorine tablets or muriatic acid.

The product itself comes as a fine white powder that’s typically pre-dissolved in a bucket before adding to pool water, though some owners prefer to slowly pour borax into their skimmer or directly in front of a return jet.

Why Use Borax in a Pool?

The main benefit of using borax to raise your pH is that it has minimal impact on your total alkalinity.

While you can also use sodium carbonate (soda ash) to significantly raise the pH level, doing so will also raise the total alkalinity by almost as much. If your alkalinity is already in a good spot, increasing it further will cause your pH to continue to rise until it’s eventually too high.

Another alternative is sodium bicarbonate (baking soda), but this will raise your total alkalinity significantly more than your pH — which is why is used primarily as an alkalinity increaser as opposed to a pH increaser.

Overall, borax is more widely used because it allows you to control pH without having to worry about how it will impact total alkalinity.

How Does Borax Work?

Borax forms a strong base (sodium hydroxide) when added to water, which naturally pushes the pH of your pool water towards being more basic.

This is similar to how soda ash works, as it also forms a strong base. The key difference, though, is that soda ash forms carbonate ions that increase your carbonate alkalinity, which ultimately increases your total alkalinity.

Borax does not produce any carbonate ions and therefore does not raise alkalinity.

Note: The only other way to raise your pH without affecting your total alkalinity is by aerating your water. It involves creating movement in the water to speed up the release of carbon dioxide, but it’s a slow process that’s only really suitable for small pH adjustments.

What Are the Other Benefits of Using Borax?

Aside from increasing pH independently of total alkalinity, borax brings a few other unique benefits to your pool.

For one, it’s a mild algaecide.

Borax introduces boron to your water which is toxic to algae in high concentrations. While you’ll never use enough borax to replace the need for sanitizer or algaecide, it will help to fortify your defense.

It’s also known to give your water a silkier, smoother feel (similar to using salt in your pool), as well as a sparkle that makes it look more luxurious and inviting. In fact, this is one of the most sought-after benefits outside of pH adjustment.

Finally, many consider borax to be less harsh than other pH increasers, including soda ash and baking soda — though neither of those substances is particularly aggressive.

Note: Some pool owners use borax for these benefits alone, meaning it isn’t strictly used for pH adjustment even if that is the most common use case.

Are There Any Borax Alternatives?

Yes – as mentioned, borax isn’t the only substance that will raise your pH level.

Each of these alternative substances will have varying effects on other areas of your water chemistry, and most notably your total alkalinity.

Baking soda slightly raises pH and raises alkalinity a lot.
Soda ash raises both pH and alkalinity by a similar degree.
Borax raises pH a lot and raises alkalinity only a little.

Which one should you use?

In most cases, it’s easier to manage your pH level using borax because it gives you precise control without inadvertently screwing up your total alkalinity.

However, if your total alkalinity also needs a boost, soda ash will allow you to kill two birds with one stone.

How to Add Borax to Your Pool (Step-by-Step)

Using borax in your pool is fairly straightforward, though the process will change slightly depending on your goal.

We’ll cover both scenarios below.

How to Use Borax to Raise pH

This section is applicable if your primary goal is to raise the pH level of your water regardless of any other benefits borax provides.

Here are the steps to follow:

Test your water. Test your pH and total alkalinity to get your starting point. We recommend using a liquid test kit over strips for better accuracy.
Run the numbers. Use this calculator to figure out how much borax to use in your pool, based on your pool volume, as well as your current pH and total alkalinity.
Prepare. Grab a bucket and fill it with water from your pool. At this point, you should make sure your pool pump is running to help circulate the borax that will be added shortly.
Add the borax. Add the calculated dosage of borax to your bucket, stir gently, and allow a few minutes for it to dissolve. We recommend using Mule 20 Team borax.
Pour the solution. Slowly pour the dissolved borax solution around the perimeter of your pool, staying close to your return jets to encourage better circulation.
Let it circulate. Keep the pool pump running for at least 24 hours after adding the borax solution to ensure it has fully circulated throughout your pool.
Check and adjust. After 24-48 hours, test your pH level once more. If it’s still too low, repeat steps 2-7.

How to Use Borax to Improve the Water

This section is applicable if your primary goal is to make your water feel silkier or smoother, give it a sparkle, or increase resistance to algae.

Note: The only major difference here is the precise addition of muriatic acid to counteract the pH increase gained from using borax.

Here are the steps to follow:

Test your water. Check your starting pH and total alkalinity, as well as your borate level. Not all testing kits will allow you to test borate, so you may need to buy a dedicated borate test strip or reagent for this.
Run the numbers. Use the same calculator above to figure out how much muriatic and borax to use in your pool. This will be based on your pool volume, pH level, total alkalinity current, borate level, and target borate level.
Mix the muriatic acid. Grab a bucket and fill it with water. Add your calculated dose of muriatic acid to the water and gently mix until dissolved.
Pour the acid solution. Turn on your pool pump to start circulating your water (leave it running throughout the rest of this process) and begin pouring your muriatic acid solution around the perimeter of your pool, near the return jets.
Mix the borax. Clean the bucket and fill it with water again. Add your calculated dose of borax to the water and gently mix until dissolved.
Pour the borax solution. Ensuring your pump is still running, pour the borax solution around the perimeter of your pool as before, staying relatively close to the return jets.
Let it circulate. Keep the pool pump running for at least 24 hours after adding the borax solution to ensure it has fully circulated throughout your pool.
Check and adjust. Test your water again after 24-48 hours. If your calculations were on point, your pH, total alkalinity, and borate level will be right where you want them. Otherwise, you’ll need to make the necessary adjustments.

Wrapping Up

So there you have it, a complete guide to using borax in a swimming pool.

If you’re looking to raise your pH without messing up your total alkalinity, borax is by far the easiest way to do it. Alternatively, borax can also help if you’re just looking to add a sparkle and softness to your water.