Published: September, 2025
Why use boric acid in your pool?
First off, we don’t sell boric acid so this post isn’t a ‘sales pitch’ for boric acid. We raise this subject because over recent years, boric acid has become a popular “secret weapon” for pool owners because it acts as a powerful supplement to chlorine. It primarily functions as a pH buffer (like baking soda) and an algaestat, making the water algae resistant, easier to maintain, and more comfortable for swimmers.
Here is a quick summary of the benefits of boric acid in swimming pools.
- Excellent pH Buffering (Especially Against Rising pH) Borates are one of the best buffers for preventing pH from drifting upward – a common issue in most pools. Borates make pH more stable around 7.4–7.8, reducing the need for muriatic acid. This is especially helpful in salt pools, where pH tends to climb quickly from salt cell.
- Algae Prevention (Algaestat, not Algaecide) Borates inhibit algae growth by interfering with algae reproduction and nutrient use (often described as “starving” algae of CO2 or disrupting cellular processes). It doesn’t kill existing algae but makes it much harder for new blooms to start, lowering overall chlorine demand by 30–50%.
- Lower Chlorine Usage With less algae pressure and more stable pH, chlorine can work more effectively. So your free chlorine lasts longer and isn’t burned up fighting minor algae issues. This means less chlorine usage, reduced chemical costs, and potentially shorter pump/filter run times.
- Improved Water Feel and Clarity, Many boric acid users report that the water feels softer and silkier on the skin when swimming. Also, water looks clearer with a subtle sparkle or tint, and reduces eye redness and dry skin after swimming. While some of these claims are subjective, they’re commonly mentioned in pool forums and reviews by pool owners.
| Feature | Sodium Bicarbonate | Boric Acid |
|---|---|---|
| Primary Effect | Raises TA + pH | Keeps pH stable ✅ |
| pH Stability | Moderate | Strong pH control ✅ |
| Algae/Mold Resistance | None ❌ | Inhibits algae growth✅ |
| Water Feel | Neutral | Softer/silkier water ✅ |
| Cost | Very low ✅ | Higher |
| Best For | Quick TA increases | Easy water care ✅ |
| Drawbacks | Regular top-ups needed ⚠️ | Overdosing risks⚠️ |
Borates Beat Baking Soda for pH Stability
The two most common chemicals used to regulate pH levels are sodium bicarbonate or boric acid. Sodium bicarbonate (AKA baking soda), is alkaline so it raises the pH level of pool water. Whereas, boric acid is a weak acid so it helps lower pH levels of pool water which reduces the amount of acid needed to balance the pool. Remember that for swimming pools, the pH is always slowly rising, so using a mild acid like boric acid will help keep the pH in the right range for longer. Boric acid works with you to help buffer pH, whereas baking soda works against you.
Maintaining the pH level of your pool water is the best thing you can do for swimmer comfort and preserving your pool surface. If the pH level is too high or too low, it can cause a number of problems, including skin and eye irritation, calcium stains, damage to pool equipment, and decreased effectiveness of chlorine. Boric acid works to maintain the pH at the right levels for a longer period.
Remember that boric acid acts as a ‘secondary buffer’ and not a complete replacement of baking soda. Small doses of baking soda may still be needed from time to time, even if you have the proper levels of borates in your pool water.
How to start using Boric Acid in Your Pool
If you decide to use boric acid in your pool, it is important to follow the instructions carefully. Always start by testing and balancing the pool water before adding anything to the pool.
The ideal range for borates is 30ppm – 50ppm. To achieve this level, you need to add around 2lbs of boric acid per 1,000 gallons of water. For example, a 10,000 gallon pool (starting with zero borates) will need around 20 lbs of boric acid to achieve 30ppm.
If your pool is larger or smaller than 10,000 gallons then obviously the amount you need to add will change. Remember, overdosing is not a good idea and can be harmful for swimmers.
Boric acid is typically sold in granular form so it is important to dissolve it in a bucket of water and then pour it slowly and evenly around the pool. While adding the dissolved acid, run the pool pump so the water is circulating. Don’t worry, most pool stores can test for borates and advise you if a top-up of boric acid is needed. Remember, borates don’t evaporate so adding boric acid to your pool is often a one-time process. It does not require constant topping-up like baking soda does.
Is Boric Acid safe for use in pools?
Many Universities across the world have studied the impact of boric acid in swimming pools. A University of Queensland study by Dr. Robert Birch evaluates boric acid as an effective secondary pH buffer and algaestat for swimming pools. At concentrations of 30–50 ppm, it successfully prevents pH drift—especially in saltwater pools—without significantly raising the (LSI).
Beyond chemical stability, his research highlights improved swimmer comfort, reduced eye irritation, and enhanced water clarity. Also, safety assessments confirm that maintaining these levels remains well within WHO health guidelines for swimmer safety.
Stop the Yo-Yo - Balancing Your pH and Alkalinity
Managing pool chemistry can feel like a “chemical carousel” because pH and Total Alkalinity (TA) move together. When you add baking soda (sodium bicarbonate) to raise your alkalinity, its high-alkaline nature naturally drives the pH up with it.
To correct that rising pH, you add muriatic acid. However, acid doesn’t just lower pH; it also neutralizes bicarbonate ions, which causes your alkalinity to drop again. This creates a frustrating loop: the acid you use to fix the pH “breaks” your alkalinity, and the baking soda you use to fix the alkalinity “breaks” your pH. To stop the cycle, focus on balancing alkalinity first and then use smaller, frequent doses of acid to gradually nudge the pH into place without crashing your TA levels.
Safety Considerations
Boric acid is a safe chemical when used as directed. However, it is important to take some safety precautions when handling it.
- Wear gloves and eye protection when handling.
- Do not ingest boric acid – if you do, call poison control or seek medical attention
- Keep boric acid out of reach of children and pets.
- If you get boric acid in your eyes, flush them with water for 15 minutes.
- Don’t overdose your pool with large amounts as this can be harmful.
Boric Acid Dosage Calculator
Boric Acid Dosage Calculator
Find out exactly how much boric acid your pool needs to reach the ideal 40 ppm borate level.
Not sure? A typical backyard pool is 10,000–20,000 gallons.
Enter 0 if untreated.
Recommended: 40 ppm.
Conclusion
Boric acid offers a great alternative to sodium bicarbonate, providing robust pH buffering without the risk of scaling. By lowering overall chemical demand and inhibiting algae growth, it streamlines maintenance while improving water clarity and swimmer comfort. It also reduces the chances of getting stains in your swimming pool. Boric acid is a fantastic upgrade for any pool owner seeking long-term chemical stability. If algae growth and green water is an ongoing issue for your pool, boric acid may be the key to breaking this cycle.
References
Birch, R (2015) Boric Acid as a Swimming Pool Buffer, University of Queensland. (Version 3 -2015)
https://poolchemistrytraininginstitute.com/guide-to-borate-for-pools/
https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Brochures/borates-swimming-pools.pdf
https://www.phta.org/pub/?id=2eadc5da-1866-daac-99fb-c832de9556fc
https://www.who.int/docs/default-source/wash-documents/wash-chemicals/boron-chemical-fact-sheet.pdf?sfvrsn=a936384f_4
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