How To Use Borax In Your Pool: Steps, When To Do It, How Much To Use & Everything Else

Written by Michael Dean
June 16, 2023

borax to use in a swimming pool

Most people remember our grandmothers’ yellow box of borax stored under their kitchen sink. My granny used it to scrub the floors; sometimes, she’d toss it in with the laundry.

But did you know borax is also great for your pool? It’s an excellent solution to your pool’s annoying pH issues and fights algae formation, leaving the pool sparkly and feeling soft.

Read this guide to learn more about using borax in your pool. And if you feel so inclined, check out some other household cleaning products you can use in your pool.

Main Takeaways

  • Borax is a chalky or powdery white substance with properties similar to table salt. It is effective in removing mildew and mold and fights algae formation.
  • Borax increases pH, acts as a pH buffer, acts as an algaecide, and has a lasting effect.
  • Your pH should be between 7.2 and 7.6, and your alkalinity should be between 80 to 120 ppm.

What Is Borax?

Borax is a chemical compound of the element boron. It’s a chalky or powdery white substance with different names, like sodium tetraborate, sodium borate, or disodium tetraborate.

You can find borax in granular and crystal form in areas with seasonal lakes that keep evaporating. Its properties are pretty similar to generic table salt. Also, like salt, it’s readily available and cheap.

Borax fights algae formation and is highly effective in removing mildew/mold. It’s also a detergent booster, insecticide, and water softener.

In recent years, this jack-of-all-trades mineral has also made a name in pool care. Let’s find out why using borax in your pool may be necessary.

When Do You Need to Add Borax to Your Pool?

Borax doesn’t decompose, expire, or get used up. It’s only lowered by water loss-drag out, splash out, filter backwashing, and leaks or draining.

Therefore, you only add it once, and unless your pool is losing a lot of water, you don’t have to add it any time soon until you empty the pool and refill it.

How to Use Borax in Your Pool Water

If your pool water pH is too low, you’ll need to raise it. A simple and effective way to do that is to use borax. All you require is a pH testing kit, borax, and safety gloves, and then follow these steps.

Here’s the basic borax powder I recommend.

20 Mule Team Borax Powder
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Step 1: Conduct a pH Test

The first step should be to check your pool water’s acidity levels. Find the pool’s capacity and current total alkalinity, and determine the amount needed to increase your pH.

Step 2: Determine the Amount of Borax to Add

Using my borax pool calculator, determine how much borax you need to add to your pool. Your water’s chemical composition is what primarily determines this.

I recommend adding about 20 ounces of borax for every 5,000 gallons of water in your pool. This amount will help increase the pH by approximately 0.5.

Step 3: Add Borax to Your Pool

Switch on your pool’s water pump and filter and let them run. Add borax to the skimmer and leave the pump to run for 24 hours.

Step 4: Re-check the pH Levels

After the 24-hour period expires, it’s time to check your pH levels to determine if you have achieved the ideal range.

You may find that it’s still low. Don’t panic. Add more borax equal to or slightly less than previous measurements depending on the new pH level.

One important thing to note is that if your pool water’s pH level exceeds the ideal range by about 0.2 or less, don’t worry. In a few weeks, this will naturally decrease. If you overshoot that range, head to my guide on lowering your pool pH level.

Also, as a safety precaution, always wear gloves when handling borax.

Benefits of Borax in a Pool

Keeping your pool water chemistry in check can be a daunting task. That’s where borax comes in. It makes it so much easier. Adding some borax to your pool will help to:

  • Increase the pH of your pool water in situations where it’s gotten highly acidic.
  • Prevent the growth of bacteria and algae.
  • Provide a buffer for pH, protecting your sanitizer levels.

Let’s look at the benefits in detail.

Increasing pH

Gone are the days when pool owners used sodium carbonate or bicarbonate (soda ash and baking soda) to help raise their pool water’s pH when things got excessively acidic. Instead, pool owners now use borax as a quicker, easier, and more effective solution.

When applied in the correct amounts, this product increases the pH of an imbalanced pool. And it does so without the process of raising the alkalinity.

Borax is not a bicarbonate compound, so its effect on the water’s alkalinity will be insignificant.

pH Buffer

While maintaining pH balance is crucial, it can be a struggle most pool owners and maintenance service providers can relate to. But this incredible compound is a white knight against pH imbalance.

Besides muscling out low pH, borax will keep your pool safe for long. It guarantees a stable pH by building a fortress around it so that any chemical changes and unseen attacks cannot affect it.


Algae and other bacterial growth are a nuisance to any pool owner. Although borax is technically not an algaecide, it does the same thing as other algaecides out there.

If you add borax to your pool in the right quantities, the pH levels will stabilize. Consequently, this allows your sanitizer to do its job perfectly.

The pH levels must be correct for your pool water sanitizer to work properly. Additionally, the total alkalinity should be at the level it needs to be. Chlorine allowed to live its best life is the best protection against algae and any other bacterial growth.

Lasting Effect

The lasting power of borax is phenomenal. While other carbonates don’t last long in a pool, borax will keep working long after dissolving.

Soda ash and baking soda are examples of such carbonates that don’t last in a pool. Their chemical nature causes them to evaporate soon after they dissolve.

But unlike these carbonates, our little champ, borax, goes nowhere. We can say it’s immortal as it will live in your water forever, continuing to work indefinitely.

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Why Are pH Balance and Total Alkalinity Important?

Achieving perfectly pH-balanced pool water is every pool owner’s dream. However, this doesn’t come easy. Many times, you struggle to maintain a stable optimal pH, only to find that the alkalinity has gone up (trust me, I’ve been there).

You’ll add soda ash or baking soda to raise the pH level, and it’ll work but then cause an annoying side effect – increased alkalinity. Then you have no choice but to add more chemicals to fix the problem.

Perfect pH

What’s a perfect pool pH? It’s a pH of between 7.2 and 7.6. Such a pH ensures your sanitizer works appropriately.

If your pool water pH rises above 7.8, brace yourself for side effects. It’ll cause a reduction of your chlorine’s cleaning power, which will subsequently allow excessive bacterial growth.

On the other hand, if the pH falls below 7.2, it’ll also affect your sanitizer’s cleaning ability. What’s more, such acidity levels can cause skin and eye irritation for people swimmers.

For these reasons, you shouldn’t allow your pool’s pH to stay at such low levels – the effects will be regrettable. You’ll start to notice a build-up of lime, and some of the concrete or stone of your pool may begin to dissolve. Ensure an optimum pH always to avoid such issues.

Perfect Total Alkalinity

Total alkalinity is a vital measurement of your pool chemistry you should take several times a week. The optimal level for total alkalinity is between 80 and 120 parts per million (ppm).

You’ll achieve that delicate balance with alkaline substances in your pool water. These substances will act as a pH buffer, so they won’t impact the balance, even when you have a pool party or when it rains.

The alkaline substance that’s a pH buffer, your pool water’s best friend, is no other than borax.

How to Boost Alkalinity When the pH is Fine

To raise your water’s pH, all you need to do is add borax. But what about when your pH is acceptable, but there’s a need to add more alkalinity? It may be necessary to include an acid in your borax to balance the pH.

Try to resist the urge to use the acid on its own. You see, borax has an extremely high pH (about 9.5). The pH will rise, and you’ll now face the stress of trying to lower it.

Similarly, adding a lot of borax to your pool can be risky as it may increase the pH too much. To ensure you don’t run into such issues, add a pH reducer such as muriatic acid.

Final Takeaway

If you’re looking for an easy and quick way to balance your pool water’s pH acid, then borax is the ideal product for you. As mentioned above, borax has several benefits. It’s also pocket-friendly and readily available. This handy product can help maintain your pool at ultimate cleanliness, and you and your loved ones can enjoy a swim in a pH-perfect, algae-free pool.

Questions about borax? Let me know.

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