Aiper AU: Pool Tips

Is Sodium Borate the Same as Boric Acid?

Aiper

• 3 min read
A box of borax and a jug of muriatic acid representing the budget-friendly but labor-intensive method of adding pool borates.

Walking down the aisle of your local hardware store or pool shop, you might feel like you need a chemistry degree to understand the labels. You see "Borax," "Sodium Borate," "Sodium Tetraborate," and "Boric Acid."

A common question we hear from Australian pool owners looking to stabilise their water is, "Is sodium borate the same as boric acid?"

The short answer is no, they are not the same, although they both come from the element boron. While they can both be used to achieve the same result (silky water and stable pH), the major difference lies in their pH levels and how you must treat your pool when adding them.

In this guide, we’ll break down the chemistry into plain English so you can make the right choice for your pool.

Table of Contents

What is Sodium Borate (Borax)?

Sodium Borate, commonly known as Borax (or chemically as Sodium Tetraborate), is a naturally occurring mineral. In Australia, you’ll often find this in the laundry section of supermarkets or at hardware stores like Bunnings.

  • Chemical Nature: It is a salt of boric acid.
  • pH Level: High (approx. 9.0 – 9.5).
  • Pool Use: Because it has a high pH, adding pure borax to your pool will drastically raise your pH.

If you use sodium borate to introduce borates to your pool, you must also add a significant amount of hydrochloric acid (muriatic acid) to counteract the pH spike.

What is Boric Acid?

Boric Acid (hydrogen borate) is essentially borax that has been processed with an acid (usually sulfuric acid) to remove the sodium. This is what you typically find in premium "Pool Borate" products sold in specialised pool shops.

  • Chemical Nature: It is a weak acid.
  • pH Level: Neutral to slightly acidic (approx. 5.0, but acts neutral in pool water buffering).
  • Pool Use: It has a negligible effect on your pool's pH.

If you use boric acid, you can usually "pour and go" without needing to mess around with large amounts of acid to balance the water.

The Key Differences Between Borax and Boric Acid

To help you decide between sodium borate vs boric acid, we’ve compared them side-by-side.

Feature Sodium Borate (Borax) Boric Acid
Common Name Borax / Laundry Booster Pool Borates
pH Level High (~9.5) Neutral (~5.0 – 7.0 effective)
Impact on Pool pH Raises pH sharply Minimal / No change
Additional Chemicals? Yes, requires Acid No, usually standalone
Cost Generally Cheaper More Expensive
Convenience Low (More work) High (Easy to use)
Two test strips comparing the high pH of sodium borate against the neutral pH of boric acid.

Sodium Borate vs. Boric Acid: Which One Should You Use?

Both chemicals will end up creating the same concentration of borates (B) in your water, which gives you that desired algaestatic effect and pH buffering. The choice comes down to budget vs. convenience.

Option A: The DIY Route (Sodium Borate / Borax)

  • Best for: Budget-conscious owners who are comfortable handling acid.
  • The Process: You buy cheap Borax from the hardware store. For every box of Borax you add, you must carefully calculate and pour a specific amount of hydrochloric acid to keep your pH from skyrocketing.
  • Risk: If you get the math wrong, your pH will be out of balance, potentially irritating swimmers' eyes or causing scale.

Option B: The Pro Route (Boric Acid)

  • Best for: Owners who want a hassle-free experience.
  • The Process: You buy a bucket of granular boric acid. You calculate the dose, add it to the pool, and brush it in.
  • Benefit: Your pH stays stable immediately. There is no need to handle dangerous quantities of acid at the same time.
A pool owner pouring granular boric acid directly into the water for a hassle-free and pH-neutral application.

A Note on "Sodium Tetraborate Pentahydrate"

You might see a product labelled Sodium Tetraborate Pentahydrate at a pool supply store. Is this the same as boric acid?

No. This is essentially a concentrated form of borax (with less water weight). Like standard Borax, it has a high pH and will require acid addition, though often less than the laundry aisle variety. Always read the Safety Data Sheet (SDS) or the label instructions.

How to Mix It Safely

Regardless of whether you choose the budget-friendly Sodium Borate or the convenient Boric Acid, proper circulation is non-negotiable.

  1. Safety Gear: Always wear gloves and eye protection.
  2. Dissolve: Brush the granules until fully dissolved to prevent damage to pool surfaces.
  3. Circulate: Run your pump.
  4. Automate: Drop in your Aiper robotic pool cleaner to ensure the water at the bottom of the pool (where heavy granules sink) is thoroughly mixed with the upper layers.
A robotic pool cleaner circulating the water to help dissolve borate granules and prevent surface damage.

Summary

So, is sodium borate the same as boric acid? Technically no, but they are close relatives.

  • Sodium Borate (Borax) is high pH and requires you to add acid.
  • Boric Acid is neutral in pH and is easier to add.

For most Aussie pool owners, we recommend boric acid for its simplicity and safety, despite the slightly higher upfront cost. It saves you the headache of fighting with your pH levels later.

References:

  • National Centre for Biotechnology Information (NCBI) – PubChem Compound Summary for Boric Acid.
  • SPASA Australia – Chemical Handling Guidelines.