Borax, also known as sodium borate, sodium tetraborate or disodium tetraborate, is a chalky, white mineral composed mainly of boron and boric acid and can be found in areas where seasonal lakes evaporate repeatedly. For the average person like me, we are most familiar with Borax as a household cleaning product. I mean who can forget that bright, yellow box under Grandma’s kitchen sink?

Borax is still a common ingredient in many laundry and cleaning products, hand soaps, and tooth bleaching formulas and can be found in a multitude of other products ranging from enamel glazes, fire retardant, and antifungal medications to pesticides and thrush medication for horses.

In recent years, this jack-of-all-trades mineral has found a new purpose: stabilizing alkalinity and acting as a pH buffer in swimming pools. Traditionally, pool maintenace companies and pool owners have used sodium bicarbonate (baking soda) or sodium carbonate (soda ash) in their efforts to keep the pH level of their pools at the optimum level.

A pH level above 7.8 can drastically reduce the chlorine’s effectiveness, which in turn allows bacterial growth to increase. A low pH level (below 7.2) can be just as harmful as it not only lowers the chlorine’s sanitizing capability but also causes redness and soreness in the eyes, skin irritations and damage to the pool’s structure as lime begins to accumulate and dissolve the granite.

However, both of these chemicals have the tendency to raise the total alkalinity of the water along with the pH. As the total alkalinity increases, it becomes easier for the pH level to fluctuate, leading you, the pool’s owner, into a vicious cycle of trying to raise the pH while balancing the total alkalinity.

What does borax do in a swimming pool?

Here’s where Borax comes to the rescue. Chemically speaking, borax, sodium bicarbonate and sodium carbonate are very similar in composition and their effect on pH. All three of these compounds are very effective as a pH buffer and when used to raise the pH level.

However, our humble Borax has an advantage over the carbonate compounds: while raising pH and acting as a buffer to prevent the pH level from fluctuating, borax does NOT raise the total alkalinity.

The most difficult struggle faced by pool owners and maintenance companies is how to maintain a steady, optimal pH without raising the total alkalinity. While baking soda and soda ash are quite effective at raising pH, they also tend to raise the alkalinity as well, forcing you to add even more chemicals to correct the imbalance.

So it seems that borax, our once-humble household cleaner has turned into a knight in shining armor riding to the rescue of our chemically imbalanced swimming pools. Not only it is extremely effective as a pH buffer (while leaving those alkalinity levels right where they’re supposed to be), it also provides some protection against algae growth.

While not techically used as an algaecide, using borax in a pool keeps the pH level steady, which allows the chlorine to effectively sanitize the water.

Another added benefit of using borax in the place of baking soda and soda ash is that once the borax is dissolved in the pool it remains in the water permanently and does not evaporate like the carbonates will. Borax is also much cheaper in comparison. That fact combined with its longevity means massive savings for you!

Using borax to raise pH in your swimming pool

It is obvious that using borax to raise pH is not only cost-effective, but also makes maintaining your swimming pool a much easier chore. However, don’t go dumping boxes of laundry booster into the backyard pool just yet.

You first need to determine the exact amount you’ll need and whether or not you’ll need to use additional products to lower acidity levels after the borax is added.

The amount of borax you need is determined by calculating how much the pH needs to be raised as well as the pool’s total alkalinity. You will also need to know the size of your pool. Don’t worry, there’s very little math involved as you can purchase a testing kit at any pool supply store.

Once you have these numbers and have chosen which product you will be using, there are numerous online water-chemistry calculators that will do all the heavy lifting and calculate how much borax will be needed. One of the dangers of using borax is its extremely high pH content which can cause low acidity levels.

You may need to add additional products along with the borax to preserve the chemical balance of the pool. Again the water-chemistry calculator will tell you exactly how much of each product you’ll need.

Before you run off to start dumping boxes of borax into your pool, read the step-by-step guide for adding borax to a swimming pool:

  1. Use a water-chemistry calculator to determine how much borax to add.
  2. With the pool’s pump and filter running, add the borax to the skimmer.
  3. Wait at least a day and retest a water sample.

Josh Hurd

Josh Hurd has been freelance writing since 2006. He attended the University of Akron, graduating with a Master of Fine Arts in creative writing.
Josh Hurd

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