What Level Should Pool Alkalinity Be?

Total alkalinity is one of the most important yet often misunderstood aspects of pool maintenance. It acts as a buffer for your pH levels, keeping the water stable and preventing rapid changes that can lead to swimmer discomfort, equipment corrosion, or cloudy water.

Fortunately, there are effective ways to correct imbalanced water, including using alkalinity buffers like baking soda (sodium bicarbonate), soda ash, or sodium bisulfate, all of which affect pH balance and total alkalinity.

As your swimming pool experts, we’ll explain what total alkalinity is, why it matters and exactly what level pool alkalinity should be. You’ll also learn how to test, adjust and maintain your pool’s total alkalinity to keep your water healthy and balanced year-round.

What is total alkalinity?

Total alkalinity refers to the concentration of alkaline substances (mainly bicarbonates) in your pool water. It’s measured in parts per million (ppm) and helps stabilise pH levels. Without enough alkalinity, your pool’s pH can swing dramatically, making it difficult to maintain water chemistry.

High or low total alkalinity in your pool can cause various issues. We can't stress this enough: it is important to regularly test and adjust the alkalinity level in your pool as part of your normal maintenance routine, no matter if you have cloudy pool water, or clear.

How alkalinity and pH are linked

Total alkalinity acts as a buffer that helps stabilise your pool’s pH levels. When your alkalinity level in pool water is within the ideal range (80–120ppm), it prevents rapid changes in pH, which can otherwise fluctuate due to rain, chemical additions, or heavy swimming use.

If total alkalinity is low, your pH may swing too easily, making the water corrosive or irritating. If total alkalinity is high, your pH can become difficult to adjust and may remain too high, increasing the risk of scaling and cloudy water. If pH remains too low it will make your water corrosive and sealing rubbers will perish and begin to leak and may cause costly repairs.

In short, keeping your total alkalinity balanced helps maintain steady pH levels, which improves the effectiveness of chlorine, protects pool surfaces, and creates a safer environment for swimmers. Always check and correct alkalinity before trying to adjust pH.

What is the acceptable level for alkalinity of water?

The ideal pool alkalinity level is typically between 80ppm and 120ppm. pH and alkalinity are linked, and this range provides effective buffering to keep your pH in check, protect your pool equipment and create a safe environment for swimmers.

Some variables (like sanitiser type or climate) might shift this slightly, but as a general rule:

• 80–100ppm: suitable for pools using chlorine or UV
• 100–120ppm: ideal for most saltwater systems

Maintaining a good alkalinity level for pool health also helps improve the efficiency of chlorine, meaning you’ll get more sanitising power from less chemical use.

How do I know if my pool alkalinity is low or high?

Testing your pool total alkalinity regularly is the only way to know if it's in range. Use a liquid test kit, digital reader, or test strips that specifically show total alkalinity. Test at least once a week, or more often during periods of heavy use or weather changes.

Low alkalinity in pool (below 80ppm)

• Signs: pH fluctuates quickly, etching of pool surfaces, skin or eye irritation
• Causes: Overuse of acid, rainwater dilution, heavy pool usage
• Labelled as: total alkalinity low, pool total alkalinity low

High alkalinity in pool (above 140ppm)

• Signs: Cloudy water, scaling, difficult to lower or raise pH
• Causes: Overuse of sodium bicarbonate, baking soda, muriatic acid, hard water sources
• Labelled as: total alkalinity high, pool total alkalinity high

How to raise alkalinity in pool

If you have low total alkalinity in pool, you need to increase total alkalinity using an alkalinity increaser. This usually comes in the form of sodium bicarbonate (baking soda), sold as a specific pool chemical for boosting alkalinity such as Alkalinity Up.

Steps to raise alkalinity in pool:

1. Test your water to confirm total alkalinity is low.
2. Calculate dosage (usually 1.5kg of alkalinity increaser per 50,000L will raise TA by 10ppm).
3. Add the increaser to the pool following the package instructions with the pump running.
4. Retest after 6–8 hours and adjust further if needed.

Adding in smaller amounts and retesting is better than overcorrecting. Raise total alkalinity in the pool gradually until you hit your target.

How to lower pool water alkalinity

High total alkalinity in pool can make pH difficult to manage and encourage scale build-up. To reduce total alkalinity in pool, you’ll need to add pool acid (hydrochloric acid or dry acid) using a slow, stepwise process.

Steps to lower alkalinity in pool:

1. Test your water to confirm total alkalinity is high in pool.
2. Turn off your pump.
3. Add the recommended dose of acid in one spot at the deep end (acid column method).
4. Let the water sit still for 30–60 minutes.
5. Turn the pump back on and allow full circulation.
6. Retest and repeat as needed.

Be cautious not to reduce pH levels too drastically while adjusting alkalinity. Monitor both during this process.

If you’re unsure how to approach it, ask Loopym or take a sample to your local pool store.

Tips for managing pool alkalinity

• Test total alkalinity weekly, and after major rain or top-ups
• Adjust slowly. Don’t try to correct the full imbalance at once
• Use the Loopym app to track changes
• Ensure other markers like pool water's pH scale and chlorine level are in balance
• Choose high-quality total alkalinity increasers and acids to avoid impurities

If your pool total alkalinity keeps drifting out of range, it may be time to look at your source water, salt system, or chemical dosing routine. Or Ask Loopym….. It will tell you everything you need to do specific to your pool. Power is in your pocket.

Why alkalinity matters for pool owners

For pool owners, understanding what total alkalinity is and how it interacts with other pool chemicals is essential, thankfully the Loopym app does all the hard work for you. Maintaining the ideal range of alkalinity reduces the amount of corrective chemicals you’ll need, improves swimmer comfort and helps extend the life of your pool surface and equipment.

Ignoring this value can lead to cascading problems. High or low alkalinity levels in pool water may not seem urgent, but left untreated, it can cause damage that’s expensive to repair.

Maintaining ideal alkalinity

So, what level should pool alkalinity be? Aim for 80ppm to 120ppm as your target total alkalinity range. This sweet spot supports water stability, maximises sanitiser effectiveness and makes your swimming pool easier to manage.

Whether you're looking to raise total alkalinity in pool, lower total alkalinity in pool, or just keep it steady, regular testing and adjustment is the key. Use a reliable total alkalinity increaser or acid, test often, and make small changes over time.

By understanding how to increase total alkalinity in pool and how to reduce total alkalinity in pool, you're taking a big step toward simpler, safer pool ownership.