Things You'll Need
Pool chemistry test kit
Soda ash

A swimming pool is an amenity that can bring hours of family enjoyment. But a pool is also a great responsibility that requires constant vigilance to keep the chemical balance of the water at proper levels. One metric of chemical balance for swimming pool water is alkalinity. The alkalinity level affects the pH of the water. If the pH is not maintained in the proper range, it could cause discomfort to swimmers. Soda ash is an inexpensive alternative to sodium bicarbonate when you need to raise the alkalinity level of the pool water.
Step 1
Test the alkalinity and the pH level of the pool water using a pool chemical test kit. Follow the directions on the test kit you have for ascertaining the pH and total alkalinity. The optimum level for alkalinity is 80 to 150 parts per million. The optimum level for pH is 7.0 to 7.6. Soda ash will raise alkalinity but it will also raise pH, so it should only be used if both test low.
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Step 2
Add soda ash to the pool water by using a method called broadcasting. Fill a container with soda ash and walk around the circumference of the pool, distributing the soda ash into the middle of the pool. Add 1.6 ounces of soda ash for every 1,000 gallons of water in the pool and for every 10 parts per million of increase in the total alkalinity that is needed.
Step 3
Wait for about two hours to allow the chemical to circulate in the water and test it again. If the alkalinity is still too low, add soda ash using the same calculation as before. Ensure that the pH level is also low before adding more soda ash.