How to Lower Alkalinity in Your Pool (and When to Raise It)

Keeping your pool water balanced is both an essential yet misunderstood aspect of pool management. Alkalinity and pH work alongside each other to determine whether your water is comfortable, safe, and gentle on your pool equipment. When either falls out of range, your entire pool system feels the effect.

Quick Answer: To lower pool alkalinity, add muriatic acid or sodium bisulfate to your water in controlled, measured doses. If you’re wondering how to lower alkalinity in pool without affecting pH, use the acid + aeration method. To raise alkalinity in a pool, add sodium bicarbonate, also known as baking soda. When in doubt, a partial drain and refill can help both levels reset.

What Is Pool Alkalinity?

Before understanding how to lower alkalinity in a pool, it’s worth understanding what pool alkalinity is.

Essentially, alkalinity is your pool’s pH stabilizer: when it’s within range, your pH holds steady, and when it’s not, your pH fluctuates. The term refers, specifically, to the concentration of alkaline substances in your pool, most of which are bicarbonates.

For most pools, the ideal alkaline range is 80-120 parts per million (ppm), but some experts recommend keeping it at 100-120 ppm for concrete and plaster pools. Your target pH range is 7.4-7.6.

When alkalinity is too high, pH becomes stuck at an elevated level and is difficult to bring down. This can lead to cloudy water, scale buildup, and reduced effectiveness of your pool sanitizer. When alkalinity is too low, and you’re trying to determine how to raise alkalinity in a pool, your pH becomes unstable. Side effects include eye and skin irritation, corrosion of metal fixtures, and damage to your pool’s surface.

How to Test Pool Alkalinity

Before adjusting anything, it’s essential to know your pool’s alkalinity. During swim season, you’ll want to test this around once a week. If there’s heavy rain or you add significant amounts of water, you’ll also want to check it then, as these events can impact your pool’s alkalinity.

There are three ways to get a reading:

Test Strips
This is the quickest and most affordable way to determine your pool’s alkalinity. Simply dip a strip into your pool, wait the recommended amount of time, and compare the strip’s color to the chart on the packaging. While convenient, test strips can be less accurate than other testing methods.

Liquid Test Kits
These use reagent drops to produce a color change, which you then compare to a reference chart. More accurate than test strips, liquid test kits are ideal for homeowners trying to get precise chemical readings before making any adjustments.

Digital Testers
Digital testers are the most accurate option available to homeowners, but they’re also the most expensive. Professionals use them, and they’re a smart investment for people who test often or have a history of water balance issues.

How to Lower Alkalinity in a Pool

If you’re seeing a reading higher than 120 ppm, it’s time to figure out how to lower alkalinity in a pool. The easiest way to do this is by adding acid to your pool water. There are two common methods to do so:

• Muriatic acid: The most commonly used option to lower pool alkalinity, muriatic acid is effective and fast-acting. That said, it requires careful handling, so ensure you wear protective gloves and eyewear.
• Sodium bisulfate (dry acid): Safer and easier to handle, you can buy sodium bisulfate in a granulated form. It doesn’t work as quickly as muriatic acid but is better for homeowners who don’t want to handle liquid chemicals.

Once you’ve tested your pool’s alkalinity, you can then calculate how much acid it needs. After doing so, slowly pour your acid of choice into the deepest part of your pool or in front of a return jet—just not near the skimmer. Allow the water to circulate for an hour, then retest, repeating in small increments as needed.

Lower Alkalinity Without Lowering pH

One of the trickier realities of pool chemistry is that lowering alkalinity also lowers your pH. If your pH is already in range, you’ll need to identify how to lower alkalinity in pool without affecting pH.

You can do so via the acid + aeration method:

1. Add a small dose of acid to lower your pool’s alkalinity and pH
2. Run your pool’s aerator, fountains, or water features to off-gas carbon dioxide and naturally raise the pH (without affecting the alkalinity)
3. Retest both levels and repeat until alkalinity stays in range and pH is stable

How to Raise Alkalinity in a Pool

If your pool’s alkalinity reading falls below 80 ppm, it’s time to determine how to raise alkalinity in pool. Sodium bicarbonate, commonly known as baking soda, is the standard solution, as it can raise alkalinity with minimal impact on pH.

You’ll want to:

1. Calculate the amount of sodium bicarbonate you need
2. Sprinkle it across the surface of the pool while the pump is running
3. Let the water circulate for at least an hour before retesting
4. Repeat as necessary until alkalinity falls between 80-120 ppm

Lower pH and Alkalinity Together

If both pH and alkalinity are elevated, a straightforward acid solution will address both issues at the same time. Just make sure you don’t add too much—retest frequently and make gradual adjustments.

When to Call a Pool Professional

Many people can manage pool alkalinity on their own when things go right. But when things go awry, balancing your pool’s chemistry can feel like you’re stuck in a science experiment you no longer want to participate in. If your alkalinity and pH levels continue to fluctuate despite repeated adjustments—if you’re seeing persistent cloudiness, scale buildup, or staining, it’s worth bringing in a professional.

White’s Pools has helped Atlanta homeowners maintain beautiful, balanced pools for over 75 years. Our team serves Atlanta, Athens, Covington, Lake Oconee, Snellville, and Watkinsville and brings the same level of care to water chemistry management that we bring to every aspect of pool care. Booking a professional assessment with us allows our experts to quickly diagnose the root cause of your water balance issues and get you and your family back to making the most of your pool.

Ready to get back to enjoying your pool? Request a professional pool maintenance service with us today.