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Borax In Your Pool: How & When To Use It

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

In the past, borax was often used as a multipurpose cleaner, used to clean everything from floors to clothes.

Today, borax is still used as a household cleaner, as it helps to remove stains and odors.

Other than within a house, borax can also work wonders on your pool.

This chemical can maintain a pool’s ideal pH level and prevent algae from forming on the surface.

Borax is great for keeping pool water soft and sparkling clean. It’s often known as a necessity when maintaining a pool.

So, how do you use borax in the first place? You’ll learn how to do so in this article, as well as some of the benefits borax can have for your pool.

Keep reading to find out more about what borax can do for your pool!

Borax: The Basics

Borax is a chemical compound of the element boron.

It looks like a white powder which is known by other names, including sodium borate, sodium tetraborate, and disodium tetraborate.

Borax is often found in seasonal lake locations. This is often in a crystal or granular form around lakes which keep evaporating.

It has a similar consistency to standard table salt. Like salt, borax is cheap to buy and readily available.

Borax prevents algae from forming in water and works very well at eliminating mold and mildew. It’s also great at softening hard water, boosting the power of detergents, and killing insects.

More recently, this versatile chemical has been used for pool maintenance. We’ll cover more about what borax can do for a pool below.

When Should You Use Borax In A Pool?

Borax doesn’t expire, degrade, or break down. Its quality only deteriorates through water loss, filter backwashing, draining, or leaks.

This means that you only need to add borax to a pool once.

Borax In Your Pool

Unless the pool loses lots of water, you don’t need to replenish its supply unless the pool is emptied and refilled.

How To Use Borax On Pool Water

If a pool’s pH level is too low, you’ll have to raise it, so the water isn’t too acidic. One of the best ways of doing this is through borax.

To do this, you just need a pH testing kit, borax, and safety gloves.

Follow the steps below to get started:

Step 1: Carry Out A pH Test

Before we can start adding the borax, we’ll need to check the pool water’s pH level.

Look for the pool’s capacity and its current alkaline level (see also ‘How To Raise Pool Alkalinity‘), then work out how much you need to raise its pH level.

Step 2: Work Out How Much Borax You Should Add

Now you can work out how much borax you should need to add to the pool. You can use a water chemistry calculator to do this.

The pool water’s chemical makeup is the main factor that affects this.

The general guidelines are to add 20 ounces of borax for every 5,000 gallons of pool water.

This ratio will roughly raise the water’s pH level by 0.5.

Keep in mind that this is an estimate, as various factors will affect how borax you should use.

You can use an online pool calculator to work out the correct amount for your pool.

Step 3: Add The Borax

After you’ve worked out how much borax you’ll need, you can add it to the pool. Remember to put on your gloves beforehand.

Turn on the pool’s filter and water pump and leave them to run. Pour the borax into the skimmer, then let the pump run for a maximum of 24 hours.

Step 4: Check The pH Level

Once a day has passed, you can now check the water’s pH level to see if the borax has worked.

Don’t worry if it’s still too low, as you can simply add more borax!

Depending on the new pH level, you can add equal or a little less borax as you did previously, but don’t add more.

Don’t worry if the pool’s pH level goes over the ideal level by under 0.2, as this will naturally lower in a few weeks.

If it exceeds the range by a large amount, you’ll need to research how to lower the pool’s pH level, as it may damage the pool later.

As stated previously, always wear your gloves when working with borax.

Advantages of Using Borax In Pools

It can be tricky to maintain your pool water’s ideal pH level, but borax makes it a lot easier to do so.

Borax has other benefits for your pool too, which we’ll cover in more detail below.

Raising pH Level

Before borax, pool owners used baking soda (see also ‘How To Use Baking Soda In Your Pool‘) and soda ash to increase the pool’s acidic pH level. Borax does this a lot more effectively.

Now, pool owners can use borax to do this more quickly and easily than before.

If borax is used in the right amounts, it can work well to increase a pool’s pH level without increasing its alkaline level.

Borax isn’t a bicarbonate compound, so it won’t have a huge effect on the water’s alkalinity.
pH Buffer

Keeping a pool at the ideal pH balance is important, but it can take a lot of effort to do so.

Borax doesn’t just raise the water’s pH level, it maintains it by defending the water from chemical changes.

Borax will keep your pool safer for longer. It will ensure that the water consistently stays at a steady pH level by creating a barrier around it.

This will prevent the water’s chemical makeup from changing and shield it from any inconspicuous attacks.

Eliminates Algae

Pool owners will know how annoying bacteria and algae growth is, but borax can help eliminate these from a pool.

Borax isn’t known as an algaecide (see also ‘ How To Use Algaecide In Your Swimming Pool ‘), but it performs the same way as other well-known algaecides.

When the correct amounts of borax are added to a pool, the chemical will neutralize the water’s pH level.

As a result, this lets pool sanitizers carry out their tasks efficiently.

Sanitizers are chemicals, like chlorine, that kill any bacteria that enter the water. Pool water sanitizers can only work if the water’s pH level is correct.

The best way to avoid algae and bacteria growing is by allowing chlorine to work efficiently on the water.

Lasting Impact

Borax can last an incredibly long time. A lot of carbonates have a shorter life span and will break down easily in a pool.

For instance, baking soda and soda ash are carbonates that break down easily within a pool. Their chemical makeup means that they will evaporate quickly after it dissolves.

On the other hand, borax will keep doing its job even after it dissolves.

Once it is added to water, it will remain in the liquid and continue to work, as long as the water remains in the pool.

pH Balance And Total Alkalinity

Every pool owner wants their pool full of perfect pH water, but achieving this isn’t easy.

You might strive to achieve a consistent optimum pH level but find later that the alkaline level has increased too much.

For instance, baking soda and soda ash will raise the water’s pH level, but these substances are known to cause increased alkalinity too.

If this occurs, you’ll have to add even more chemicals to neutralize the water again.

Optimum pH

A pool’s best pH level lies between 7.2 and 7.6. To picture this, the pH scale runs from 0 to 14.

The lower end is acidic, while the higher end is alkaline.

A pH level around 7 will ensure pool sanitizers can do their job well.

If pool water rises above 7.8, it will become alkaline, which can cause side effects. One of these is lowering the effectiveness of chlorine.

If chlorine cannot work efficiently, bacteria will have a greater chance of accumulating within the pool.

If the pool’s pH level decreases below 7.2, the water will become acidic, which can also make the sanitizer less effective.

Acidic pool water can also irritate the skin and eyes of those that swim in it.

This is why you should always prevent your pool from staying at a low pH level.

Acidic water can make lime accumulate within the pool, and can even start to chip away at the pool’s stone or concrete.

Try to keep a regular eye on the pool’s pH level to avoid these issues later.

Optimum Total Alkalinity

Total alkalinity is another measurement of your pool water’s chemistry.

You should measure this a few times a week to ensure the water stays balanced. A pool’s optimum total alkalinity lies between 80 and 120 ppm (parts per million).

Alkaline substances within the pool water will keep it at a decent total alkalinity level.

These alkaline components perform as a pH barrier, defending the water from chemical changes.

This balance won’t change even if it rains or a lot of people swim in the pool.

This alkaline substance we will need for this purpose is none other than borax.

Disadvantages Of Using Borax In Pools

Borax is great to use in your pools, but remember that it is a toxic chemical. Some do worry about its effect on pets, like cats and dogs.

Nevertheless, this drawback isn’t due to the compound itself, but the negligence of the user.

Like all pool chemicals, borax shouldn’t be consumed. Always be careful and prevent humans and pets from coming into contact with it.

Increasing Alkalinity At Optimum pH Level

So, we’ve covered that adding borax to pool water can raise the water’s pH level.

However, this doesn’t explain what you should do if the water is at an optimum pH level, but not at the right total alkalinity.

In this case, you may need to add an acid alongside borax to neutralize the pH again.

It can be tempting to use acid on its own, but this should be avoided.

This can make the pH level decrease too much, so you’ll need to go through the trouble of raising it again.

On the other hand, adding lots of borax to the pool isn’t recommended.

Borax has a very high pH of roughly 9.5, which can make the pool water’s pH level increase too much.

You can avoid these issues from occurring by using a pH reducer, like muriatic acid.


Borax is a safe pool chemical that helps maintain the ideal pH level in your pool. It can also eliminate algae and bacteria, keeping your pool water clean and comfortable to swim in.

It’s affordable and readily available, and you only need to add it to your pool water once!

However, it is important to know how to use it correctly.

Always wear gloves when adding borax to your pool, and keep it out of reach from children and pets.

You should also work out the correct amount to add to your pool, as this will avoid the pH level increasing or decreasing by too much.

Borax is a great way to keep your pool water clean so that you and your friends can enjoy the comfort of a healthy, bacteria-free pool.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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