If you own a pool, you know how important it is to keep the water chemistry balanced. One of the key factors that affects the water quality is the total alkalinity, which measures the water’s ability to resist changes in pH. Total alkalinity acts as a buffer that stabilizes the pH level and prevents it from fluctuating too much.
The ideal range for total alkalinity in pool water is between 80 and 120 parts per million (ppm). If the total alkalinity is too low, the pH level can drop and cause the water to become corrosive, damaging the pool surfaces and equipment. If the total alkalinity is too high, the pH level can rise and cause the water to become cloudy, scaling, and prone to algae growth.
To avoid these problems, you need to know how to put alkalinity in the pool and how to lower it if necessary. In this article, we will show you how to test, adjust, and maintain the total alkalinity in your pool using simple methods and products.
How to Test Total Alkalinity in Pool
Before you can put alkalinity in the pool, you need to know what your current level is. You can test the total alkalinity in your pool using a test kit or test strips that measure both pH and total alkalinity. Follow the instructions on the package and compare the color of the test result with the color chart provided.
Alternatively, you can use a digital test kit or a pool calculator app that can give you more accurate readings and recommendations. Some pool stores also offer free water testing services if you bring a sample of your pool water.
You should test your pool water at least once a week or more often if there are changes in weather, usage, or chemical additions. The best time to test your pool water is in the morning before anyone uses the pool or adds any chemicals.
How to Raise Total Alkalinity in Pool
If your test result shows that your total alkalinity is below 80 ppm, you need to raise it to prevent pH fluctuations and corrosion. The most common and effective way to raise total alkalinity in the pool is by adding sodium bicarbonate (baking soda) to the water.
To calculate how much baking soda you need to add, you can use a pool calculator app or follow this formula:
- Multiply your pool volume (in gallons) by 1.5
- Divide the result by 10,000
- Multiply the result by the amount of ppm you want to raise your total alkalinity
- The final result is the amount of baking soda (in pounds) you need to add
For example, if you have a 10,000-gallon pool and you want to raise your total alkalinity by 20 ppm, you need to add:
- (10,000 x 1.5) / 10,000 = 1.5
- 1.5 x 20 = 30
- You need to add 30 pounds of baking soda
To add baking soda to your pool, follow these steps:
- Turn off your pool pump and heater
- Use a bucket to dissolve the baking soda in warm water
- Pour the solution around the perimeter of your pool
- Turn on your pool pump and let it run for at least 6 hours
- Retest your total alkalinity and pH levels
How to Lower Total Alkalinity in Pool
If your test result shows that your total alkalinity is above 120 ppm, you need to lower it to prevent pH spikes and scaling. The most common and effective way to lower total alkalinity in the pool is by adding muriatic acid (hydrochloric acid) or dry acid (sodium bisulfate) to the water.
To calculate how much acid you need to add, you can use a pool calculator app or follow this formula:
- Multiply your pool volume (in gallons) by 2.1
- Divide the result by 10,000
- Multiply the result by the amount of ppm you want to lower your total alkalinity
- The final result is the amount of acid (in fluid ounces) you need to add
For example, if you have a 10,000-gallon pool and you want to lower your total alkalinity by 20 ppm, you need to add:
- (10,000 x 2.1) / 10,000 = 2.1
- 2.1 x 20 = 42
- You need to add 42 fluid ounces of acid
To add acid to your pool, follow these steps:
- Turn off your pool pump and heater
- Use a bucket to dilute the acid with water (always add acid to water, not vice versa)
- Pour the solution slowly into one spot in the deep end of your pool
- Turn on your pool pump and let it run for at least 6 hours
- Retest your total alkalinity and pH levels
How to Maintain Total Alkalinity in Pool
Once you have adjusted your total alkalinity to the ideal range, you need to maintain it by monitoring your pool water regularly and adding chemicals as needed. Some factors that can affect your total alkalinity include:
- Rainwater: Rainwater is slightly acidic and can lower your total alkalinity. To prevent this, you can cover your pool when it rains or add baking soda after heavy rainfall.
- Chlorine tablets: Chlorine tablets have a low pH and can lower your total alkalinity. To prevent this, you can use stabilized chlorine tablets that contain cyanuric acid, which helps buffer the pH and total alkalinity. You can also add baking soda periodically to replenish your total alkalinity.
- pH increasers and decreasers: pH increasers (soda ash) and decreases (dry acid) can also affect your total alkalinity. Soda ash can raise both your pH and total alkalinity, while dry acid can lower both. To prevent this, you can use alternative products that have less impact on your total alkalinity, such as borax or vinegar to raise pH, and aeration or carbon dioxide to lower pH.
The Bottom Line
Total alkalinity is an essential factor in keeping your pool water balanced and healthy. By testing, adjusting, and maintaining your total alkalinity in the pool, you can prevent pH fluctuations and protect your pool from corrosion, scaling, and algae growth.