If you’ve ever tested your pool water and seen a reading for total alkalinity, you might have wondered exactly what it means, why it matters, and how to keep it in the right range.
In short, total alkalinity (TA) is one of the key pillars of pool water chemistry. If it’s too low or too high, your pH can swing wildly, leading to cloudy water, scaling, corrosion, or even skin and eye irritation.
In this guide, we’ll break down what total alkalinity in a pool is, why it’s important, the ideal levels, and how to adjust it for crystal-clear, balanced water.
Understanding Total Alkalinity
Total alkalinity is the measure of the water’s ability to resist changes in pH. Think of it as a buffer that stops your pH from jumping up or down too quickly.
It measures the concentration of alkaline substances in the water—primarily bicarbonates, carbonates, and hydroxides—expressed in parts per million (ppm).
Without adequate alkalinity, your pool’s pH can fluctuate dramatically, which makes maintaining balanced water much harder.
See also: Technology’s Role in Bridging the Digital Divide
Why Is Total Alkalinity Important?
Keeping your total alkalinity within the recommended range helps:
- Stabilise pH: Prevents sudden pH changes that can cause discomfort and equipment damage.
- Protect surfaces and equipment: Avoids corrosive water that eats away at metal fixtures, pool heaters, and plaster surfaces.
- Improve chemical efficiency: Balanced TA makes chlorine and other sanitising agents more effective.
- Prevent scaling and cloudiness: High TA can cause calcium to precipitate, creating scale on tiles and making water look dull.
The Ideal Range for Total Alkalinity
For most swimming pools, the ideal total alkalinity range is:
- Concrete, plaster, or tiled pools: 80–120 ppm
- Vinyl or fibreglass pools: 100–150 ppm
Keeping your TA within these levels ensures stable pH and comfortable swimming conditions.
How to Test Total Alkalinity
Testing is straightforward and should be part of your regular pool maintenance routine. You can use:
- Test strips: Quick and easy but less precise.
- Liquid test kits: More accurate and cost-effective for long-term use.
- Digital testers: Provide precise readings but are more expensive.
It’s best to test your total alkalinity at least once a week during swimming season and every 2–4 weeks in winter.
How to Adjust Total Alkalinity if It Is Too Low
Low TA means your water doesn’t have enough buffering capacity, causing pH to swing wildly. This can lead to corrosion, staining, and irritation.
To raise TA:
- Add sodium bicarbonate (bicarb soda) to the pool.
- Spread it evenly across the pool surface while the pump is running.
- Retest after 6–12 hours and repeat if needed.
Tip: Always raise TA before making pH adjustments, as correcting TA often brings pH closer to the right range.
How to Adjust Total Alkalinity if It Is Too High
High TA can make pH stubbornly high, cause scaling, and reduce chlorine effectiveness.
To lower TA:
- Add pool acid (hydrochloric acid or dry acid) to lower pH to around 7.0–7.2.
- Aerate the water (run water features, point return jets upwards) to bring the pH back up without raising TA.
- Repeat until TA is in the target range.
Common Causes of Total Alkalinity Problems
- Rainwater dilution: Heavy rainfall can lower TA.
- Top-ups with hard water: Can gradually raise TA over time.
- Excessive chemical use: Some sanitising chemicals affect TA.
- Neglected maintenance: Skipping testing and adjustments allows levels to drift.
Total Alkalinity and Other Pool Chemistry Factors
Total alkalinity doesn’t work in isolation—it’s closely tied to:
- pH: TA helps keep pH stable. Unbalanced TA leads to constant pH correction.
- Calcium hardness: High TA combined with high calcium increases scaling risk.
- Sanitiser efficiency: Chlorine works best in water with balanced TA and pH.
Regular pool cleaning helps maintain the long-term chemistry of your pool water. Using an automated tool like a pool cleaner can save your time and effort.
Seasonal Tips for Managing Total Alkalinity
Summer:
- Test TA twice a week due to heavy usage and higher evaporation.
- Keep an eye on TA after topping up water.
Autumn/Winter:
- Test every 2–4 weeks, as reduced usage means slower changes.
- Prevent rainwater from overflowing into the pool.
Spring:
- Test and adjust TA before swimming season starts.
- Balance TA before shocking the pool.
Final Word
Understanding what total alkalinity in a pool is—and keeping it in the correct range—is one of the easiest ways to avoid expensive repairs, water quality issues, and endless chemical adjustments. Make TA testing part of your weekly maintenance routine, and consider investing in the best pool cleaner. Your pool will remain balanced, clear, and enjoyable year-round.
