Baking soda, known chemically as sodium bicarbonate, is a readily available and cost-effective compound used to manage pool water chemistry. It is employed to address instances of low pH and low Total Alkalinity (TA), common problems that affect pool comfort and equipment longevity. Using this household item requires understanding its specific effect on water chemistry to ensure a safe and balanced swimming environment.
Understanding pH and Total Alkalinity
Maintaining proper water balance is important for swimmer comfort, the life span of pool equipment, and sanitizer efficiency. The pH level measures the acidity or basicity of the water on a scale of 0 to 14. An ideal pool pH range is between 7.4 and 7.6, which closely matches the pH of the human eye. Water below this range is acidic and can cause eye and skin irritation, while also becoming corrosive to metal fittings and pool surfaces.
Total Alkalinity (TA) is a separate but related measurement of the concentration of alkaline substances. This measurement is usually maintained between 80 and 120 parts per million (ppm) and is referred to as the water’s buffering capacity. Low TA means the water lacks the necessary buffers to prevent dramatic shifts in pH, leading to what is often called “pH bounce.” Balancing the TA is usually addressed before making fine-tuned adjustments to the pH.
How Sodium Bicarbonate Impacts Pool Chemistry
Sodium bicarbonate’s primary role in pool maintenance is to increase the Total Alkalinity of the water. When dissolved, the bicarbonate ions introduce alkalinity, raising the buffering capacity. This increased buffering capacity helps stabilize the pH, preventing corrosive low-pH conditions. While baking soda slightly raises the pH, its effect is much more pronounced on the TA.
This distinguishes it from commercial products like soda ash (sodium carbonate), which are formulated to deliver a large, rapid increase in pH. Soda ash is preferred when the pH is low but the TA is already acceptable. If both pH and TA are low, sodium bicarbonate is the safer initial choice because it gently raises TA, which helps stabilize the pH. Prioritizing the buffering capacity avoids the risk of overshooting the pH target and causing scaling or cloudy water.
Calculating the Needed Quantity of Baking Soda
The precise amount of baking soda required depends on your pool’s volume and the current Total Alkalinity (TA) reading. The standard dosage is 1.5 pounds of sodium bicarbonate for every 10,000 gallons of pool water, which typically raises the TA by approximately 10 ppm. To apply this, first determine your pool’s volume in gallons and the current TA reading from your test kit.
Example Calculation
If you have a 15,000-gallon pool and your TA is 60 ppm, aiming for 100 ppm requires an increase of 40 ppm. To raise the TA by 10 ppm in a 15,000-gallon pool, multiply the standard dosage by 1.5 (1.5 lbs x 1.5 = 2.25 lbs). Since a 40 ppm increase is needed (four increments of 10 ppm), the total calculated dose is 9 lbs (2.25 lbs x 4).
It is important to never attempt to raise the TA by more than 10 to 20 ppm in a single application. Large chemical additions risk overshooting the target and causing a complicated chemical imbalance. Therefore, add only a portion of the total calculated amount, such as 3 pounds, and retest the water after circulation.
Step-by-Step Application and Testing Guide
Before adding chemicals, ensure you have accurately tested the water and calculated the correct, incremental dosage. With the circulation system running, sodium bicarbonate can be added directly to the pool water. Slowly broadcast the powder across the surface, particularly over the deep end, to help it dissolve and circulate efficiently.
Allow the pool’s pump and filter to run for at least 6 to 12 hours. This period ensures the chemical is fully dissolved and evenly distributed. After circulation, retest the pool water to measure the new TA and pH levels. If the TA is still below the desired range of 80 to 120 ppm, repeat the process with another small, calculated dose. Making minor adjustments based on the retest prevents the mistake of adding too much chemical at once and creating a new imbalance.