What Is Alkalinity and Why It Matters
What is Alkalinity?
With any pool or hot tub, one of the most important jobs is regularly testing the water to keep it safe. Among the key parameters to monitor are disinfectant levels (chlorine or bromine), pH, and alkalinity. But what exactly is alkalinity?
Alkalinity, usually referred to as total alkalinity, measures the amount of alkaline salts (carbonates and bicarbonates) in the water, expressed in ppm or mg/L. It also indicates the water’s resistance to pH changes: the higher the alkalinity, the greater the water’s buffering capacity. Pure water has very little buffering, which makes it prone to sudden pH swings when chemicals are added—a phenomenon sometimes called “pH bounce.” If alkalinity is too high, pH can “lock” and become difficult to adjust.
With any pool or hot tub, one of the most important jobs is regularly testing the water to keep it safe. Among the key parameters to monitor are disinfectant levels (chlorine or bromine), pH, and alkalinity. But what exactly is alkalinity?
Alkalinity, usually referred to as total alkalinity, measures the amount of alkaline salts (carbonates and bicarbonates) in the water, expressed in ppm or mg/L. It also indicates the water’s resistance to pH changes: the higher the alkalinity, the greater the water’s buffering capacity. Pure water has very little buffering, which makes it prone to sudden pH swings when chemicals are added—a phenomenon sometimes called “pH bounce.” If alkalinity is too high, pH can “lock” and become difficult to adjust.
Ideal Levels
To avoid pH bounce or lock, aim for a total alkalinity between 80–160 ppm. Levels below 80 ppm can reduce water stability and affect the performance of flocculants and clarifiers. Commercial alkalinity increasers are available if the water needs raising, while lowering alkalinity is more challenging.
To avoid pH bounce or lock, aim for a total alkalinity between 80–160 ppm. Levels below 80 ppm can reduce water stability and affect the performance of flocculants and clarifiers. Commercial alkalinity increasers are available if the water needs raising, while lowering alkalinity is more challenging.
How to Test
Alkalinity can be measured using rapid tablet test kits, which are easy to use, accurate, and reliable. You can also use electronic devices, such as the Scuba II, which provide clear digital readings for easier monitoring.
Alkalinity can be measured using rapid tablet test kits, which are easy to use, accurate, and reliable. You can also use electronic devices, such as the Scuba II, which provide clear digital readings for easier monitoring.
Should I Be Worried?
It’s important to know your total alkalinity alongside other water chemistry levels. Regular testing is especially important in hot tubs, where the smaller water volume means conditions can change quickly. Always test before the first use of the day. Poor water chemistry can lead to serious issues.
Try to maintain alkalinity between 80–160 ppm where possible. However, local water conditions can affect this—some areas of the UK have naturally high alkalinity in mains water. If alkalinity is high but the water is safe, clear, and has the correct pH and disinfectant levels, monitor the readings rather than adding chemicals unnecessarily.
In short: know, monitor, and adjust alkalinity as needed, but don’t chase levels at the expense of pH or disinfectant. Properly balanced water is the key to safety and comfort.
It’s important to know your total alkalinity alongside other water chemistry levels. Regular testing is especially important in hot tubs, where the smaller water volume means conditions can change quickly. Always test before the first use of the day. Poor water chemistry can lead to serious issues.
Try to maintain alkalinity between 80–160 ppm where possible. However, local water conditions can affect this—some areas of the UK have naturally high alkalinity in mains water. If alkalinity is high but the water is safe, clear, and has the correct pH and disinfectant levels, monitor the readings rather than adding chemicals unnecessarily.
In short: know, monitor, and adjust alkalinity as needed, but don’t chase levels at the expense of pH or disinfectant. Properly balanced water is the key to safety and comfort.
Purchase a Pool Tester?
Scuba3s - Smart electronic pool tester for precise, effortless pool and spa control
The Scuba3s takes the guesswork out of pool care, combining fast, reliable testing of all essential water parameters with wireless NFC and the Lovibond PoolAssistant app. Get instant results, helpful insights, and practical water-care guidance. With intuitive operation, a compact waterproof design, and smart mobile management, the Scuba3s keeps your pool water under control—quickly, confidently, and effortlessly.
Pool Testers - Fast, Accurate, and Easy to Use
The tester combines rapid-dissolving RAPID tablets with simultaneous measurement of water treatment agents and pH, delivering highly accurate results you can trust. Its intuitive design makes operation simple and straightforward, with clear instructions to guide you whenever needed. The ergonomically optimized lid ensures a secure grip for comfortable handling every time.
Tablet Refill Packs for Accurate Water Testing
Lovibond tablet refill packs are formulated to deliver fast-dissolving, highly accurate measurements you can rely on. Designed specifically for use with Lovibond testers and the Scuba3s, the tablets ensure consistent colour development for precise water quality analysis. Easy to handle and clearly labelled, they support quick testing, dependable results, and confident pool and spa water management.
