Photo: pool-coping.net.au
Most people mistakenly use high pH in place of alkalinity but these two are a bit different. Alkalinity does affect pH by causing it to rise but alkalinity can be defined as a measure of how much acid the water can neutralize.
That said, a pool’s alkalinity is measured as Total Alkalinity (TA) and the recommended range is between 80 and 120 ppm (parts per million). If it goes above 120 ppm, the pH is likely to rise above the recommended range of about 7.2-7.6 points.
In this article, we consider a scenario where the alkalinity is too high and we give detailed steps on how to lower it.
In this post:
What Causes High Alkalinity in Pools?
The most common culprit is baking soda (sodium bicarbonate), which is used to raise the alkalinity if it is too low. If you add too much, this will cause high alkalinity.
Other than that, your water source can also be the cause of your pool’s high alkalinity. This could either be the municipal water or borehole water.
Why Do I Need to Lower Alkalinity in My Pool?
Total Alkalinity determines the pH level’s stability. If it is above the 120-ppm mark, this will raise the pH, which will reduce the effectiveness of chlorine in killing germs in the water.
Additionally, by raising the pH, the water will become cloudy and this will reduce visibility when swimming. Cloudiness also makes the water appear murky, which might ruin your swimming experience.
Lastly, high alkalinity causes scale build-up, which will clog your filters and line the pool’s walls. You can also expect itchiness on the skin and eyes, though this is not as profound as when dealing with a low pH.
How to Lower Alkalinity in Pools
Photo: pool-coping.net.au
To lower the TA, you need a test kit that checks for TA and the pH level. You also need muriatic acid. With these:
1. Test the TA and pH
There are different varieties of test kits that you can use for this step. The most common ones are testing strips but we recommend the liquid types; they are more accurate.
With this reliable test kit, scoop some water from the deepest part of the pool then run the tests. If both the TA and pH are higher than 120 ppm and 7.6 points respectively, proceed to step 2.
2. Measure and Pour in the Muriatic Acid
Muriatic acid is sold either in diluted or concentrated form. Read the manufacturer’s instructions on the bottle to determine the amount of acid required to lower the alkalinity. The target should be under 120 ppm but you should aim for about 100 ppm.
After determining and measuring the required quantity, turn off the pool pump then leave the water to remain still for about an hour. Pour the muriatic acid to the deepest part of the pool then let it sit for about an hour.
Turn on the pool pump and allow the water to circulate for about 5 to 6 hours.
3. Retest
Test the pH and TA levels again and if they have lowered to the recommended level, well and good. You should also test again after 24 and 48 hours and if the pH drops too low, you should correct this via aeration.
The pH can drop too low if you added excess acid, but you can use fountains, spa jets, air compressors, waterfalls, or any other aerators to raise the pH level. This process infuses carbon dioxide from the air with water to form carbonic acid, which corrects this mistake.
Conclusion
All in all, lowering a pool’s alkalinity can be a very slow process as compared to raising the pH level. The process takes time and there is a high chance that you might lower the pH level below the recommended level.
Therefore, apply some patience and once you hit the right spot, ensure you keep the alkalinity in check to avoid redoing this lengthy task.