Proper maintenance of a swimming pool includes monitoring and balancing the chemical components in the water, and of these chemical components, the pH level is the most important. The pH level in your pool indicates how acidic or basic the pool water is. If the pH level is too high or too low, the water could damage a swimmer's eyes, and could also become corrosive. Soda ash, or sodium carbonate, is used to raise the pH level in the event that it becomes too low for safety, and can be added to a swimming pool relatively easily.
Take a reading of your pool water with your chemical tester; see the Pool Center resource section for more information. If the pH level is below 7.4 you will need to add soda ash to your pool to bring it into the 7.4 to 7.6 range, which is mildly basic.
Consult your pool manual to determine how many gallons of water it holds, and consult the chart Raising pH With Soda Ash in the Division of Environmental Health reference to determine the amount of soda ash needed to raise the pH to the desired level. However, you should never add more than two pounds of soda ash per 10,000 gallons to your pool water; if the pH is only a little off, you will add significantly less.
Turn on your pool pump before adding the soda ash, otherwise the ash may not dissolve properly.
Put on your rubber gloves and open the soda ash container. Use your cup or scoop to add soda ash to the pool water.
Continue pouring soda ash into the pool water until you have reached the recommended dosage. Don't pour it all into one place. Instead, scatter it around the edge at the deep end of the pool. Remember not to add more than two pounds of soda ash per 10,000 gallons in a single treatment.
Re-test your pool after one day to determine if more soda ash treatments are needed.