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Go back The total alkalinity of the pool is the water’s ability to buffer pH changes; when it is too high, the pH rises continuously, the water becomes cloudy, and the disinfectant works less effectively.
It is measured with strips, drop kits, or digital meters, aiming for an ideal range of 80–120 ppm. To lower it, stop using alkalizing products and apply pH reducers (acids) in controlled doses, measuring again after several hours and repeating if necessary.
Weekly monitoring of pH and alkalinity, with small and frequent adjustments, helps keep the water clear, stable, and more comfortable for swimming.
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Close formIf your pool’s pH does not stabilize, the water easily becomes cloudy, and you use more product than normal, the problem is probably related to total alkalinity.
Understanding this is essential to effectively and safely lowering the alkalinity of your pool.
What is pool alkalinity and why does the pH rise?
Total alkalinity measures the amount of salts with buffering capacity in the water (mainly bicarbonates). Its function is to buffer pH changes.
When alkalinity is within range, the pH remains stable. If it is too high, the pH tends to rise continuously and is very difficult to correct.
Difference between alkalinity and pH in water
Although they are related, they are not the same:
- The pH indicates whether the water is acidic or basic (ideally between 7.2 and 7.6).
- Total alkalinity indicates the water’s ability to resist pH changes and is measured in ppm.
You can adjust the pH, but if the alkalinity remains high, the value will shoot back up in no time.
Main causes of high alkalinity in swimming pools
The most common causes are:
- Tap water with high carbonate content.
- Frequent refilling due to evaporation.
- Continued use of alkalizing products.
- Excessive corrections to compensate for acidic water.
How to measure pool alkalinity correctly
Before thinking about how to lower pool alkalinity, you need to know where you are starting from. A reliable measurement also depends on the condition of the pool’s filtration system, as this influences the overall water quality.
Simple methods for measuring alkalinity
The most common systems are:
- Test strips: quick and easy to interpret.
- Drop kits: slightly more accurate.
- Digital meters: useful for frequent checks.
Take the sample at mid-depth, away from nozzles and skimmers, and analyze immediately.
Recommended total alkalinity values
In most pools, the recommended range is between 80 and 120 ppm. This table will help you interpret the result:
| Measured alkalinity (ppm) | Water condition | What to do |
| < 80 | Low alkalinity, unstable pH | Increase alkalinity with specific products |
| 80–120 | Recommended and stable range | Maintain and monitor regularly |
| 120–180 | High alkalinity | Begin gentle corrections with reducing products |
| > 180 | Very high alkalinity, pH difficult to control | More intensive correction plan and frequent measurements |
Above the ideal range, the water may become less clear and begin to appear cloudy.
Consequences of high alkalinity in the pool
Problems caused in the water and equipment
When alkalinity is excessive, the following may occur:
- Chronically high pH, which does not remain within the range.
- Reduced disinfectant effectiveness and risk of the water turning green.
- Scale and deposits on linings, ladders, and equipment.
How to tell if alkalinity is too high
In addition to testing, you can suspect high alkalinity if:
- The pH rises again shortly after correcting it.
- You need more and more product to lower it.
- You notice whitish stains on the waterline or metal elements.
If several of these symptoms occur, it is very likely that the alkalinity is above the recommended level.
How to safely lower the alkalinity of your pool
Follow these steps to lower the alkalinity in a controlled manner:
- Measure the initial alkalinity and pH: Write down both values so you can check the effect of each correction later.
- Stop using products that increase alkalinity: Stop adding alkalinity increasers or other alkalizing products while the adjustment is in progress.
- Apply pH reducers: Acids, i.e., pH reducers, are used to decrease alkalinity.
- Follow the manufacturer’s recommended doses.
- Dilute the product in a bucket of water and distribute it around the pool, with the filtration system running.
- Let the water circulate and measure again: After several hours of recirculation, measure the pH and alkalinity again.
- If the alkalinity is still high, repeat the process with small successive doses.
- Avoid sudden corrections so as not to upset other parameters.
- Adjust the final pH: When the alkalinity is between 80–120 ppm, correct the pH if necessary until it is between 7.2 and 7.6.
Tips for maintaining long-term water balance
- Check pH and alkalinity at least once a week, not just chlorine; combine these checks with basic pool maintenance practices.
- Monitor the effect of water refills and rainfall with subsequent measurements.
- Avoid making sudden corrections: it is better to work with small, frequent adjustments.
For more stable management, you can support control with water treatment automation systems (excluding brands and links removed).
Good alkalinity control from the start translates into a more comfortable, efficient pool that is ready to offer a more enjoyable swimming experience.