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Borax can be used in swimming pools to maintain pH levels, control algae growth, and prevent the formation of scale. To use borax, first, test the pH level of the pool water. If the pH is below 7.2, add borax to increase it. Start with 20 ounces of borax per 10,000 gallons of water and test again after 24 hours. If the pH is still low, add more borax in small increments. To control algae, add 1.5 pounds of borax per 10,000 gallons of water weekly. To prevent scale formation, add 1.25 pounds of borax per 10,000 gallons of water every other month. Remember to always follow the manufacturer’s instructions and consult a professional if needed.
Borax is a commonly used and inexpensive household product that is highly effective in keeping swimming pool water clean and comfortable for swimmers. It contains boron, which helps to suppress algae growth, and its chemical properties aid in stabilizing pH levels and reducing the need for excessive chlorine usage. However, understanding the chemistry behind its usage is essential for successful pH buffering and alkalinity stabilization.
Pool pH and Alkalinity
Maintaining the proper pH level in a swimming pool is crucial. High pH levels can render chlorine disinfectant ineffective, while low pH levels can cause eye and skin irritation, as well as damage to pool equipment and surfaces. Ideally, pool water should have a pH range of 7.2 to 7.6.
Alkalinity is also important as it acts as a buffer against pH fluctuations. When the water’s total alkalinity falls within the recommended range of 80 to 120 parts per million, pH levels are usually stable and easier to maintain.
Baking Soda and Soda Ash
Sodium bicarbonate, commonly known as baking soda, and sodium carbonate, also referred to as soda ash, are two chemicals often used to adjust pH and alkalinity in swimming pools. Adding baking soda raises both pH and total alkalinity, making it unsuitable when pH is low but total alkalinity is normal. Soda ash, on the other hand, is less likely to raise total alkalinity when used properly to increase pH, although excessive use can still cause issues.
Sodium Tetraborate
Sodium tetraborate, commonly known as borax, is another solution for pH buffering and increasing in pool water. Unlike baking soda and soda ash, it does not raise total alkalinity due to its non-carbonate nature. Additionally, borax helps keep the water clear and prevents algae growth by stabilizing pH within the appropriate range.
To act as a pH buffer, borax should be present in the water at a concentration of 30 to 50 ppm. Some borax products contain sodium tetraborate decahydrate, while others contain sodium tetraborate pentahydrate, which has a higher boron content per mass and requires smaller amounts to function as a buffer.
One drawback of borax is its high pH level, around 9.5. When added in large quantities, it significantly raises the water’s pH. To counteract this, muriatic acid or another pH-reducing product can be added alongside borax to bring the pH back to appropriate levels.
How to Use Borax
If the goal is solely to increase pH, borax alone may be sufficient. However, if the intention is to raise the water’s borate level for pH buffering and the pH level is already correct, both borax and acid may need to be added to achieve the desired results.
The quantity of borax needed will vary depending on the initial pH level and total alkalinity of the water, the size of the pool, the type of borax product used, and the desired water chemistry goals. An online calculator for water chemistry can determine the amount of borax to be added and whether acid is also needed based on the specific conditions and goals of the pool.
To raise the pH using borax, first use the calculator to determine the necessary amount of borax to achieve the desired change. With the pool’s pump and filter operating, add the recommended amount of borax to the skimmer. Wait for a day and then test the pH again. If needed, add more borax to reach the desired pH level. If the calculator indicates the need for both borax and acid, start by adding half of the required amount of acid, followed by half of the recommended amount of borax. Brush the pool walls to help dissolve the borax into the water.
Once the initial application of borax is dissolved, add the remaining acid, followed by the remaining borax. Brush the pool again and keep the pump running for 24 to 48 hours. After 48 hours, test the pH of the water and add more acid if necessary to adjust it to the correct level.
