An acid demand test determines how much acid is required to decrease the swimming pool water pH level.
What is an Acid Demand Test?
An acid demand test measures acid demand, which is the amount of an acid needed to reduce the pH level measured in a body of water. The test results are then extrapolated to the appropriate volume of water to determine the approximate amount of acid to add to the water. Acid demand tests can be affected by the water alkalinity level. As the alkalinity increases, more acid demand reagent is required to conduct the test, indicating more acid will be required to lower the water alkalinity.
How is an Acid Demand Test performed?
For swimming pools, an acid demand test is usually performed by titration, where an acid demand reagent is added drop-by-drop to a water sample. The number of reagent drops added indicate how much acid to add to the pool water to decrease the pH level and bring it closer to a balanced state.
Acid demand tests are also useful prior to testing pool water pH when the pH level is suspected of being extremely high. The acid demand test will indicate how much acid to add to the water, which after adding and allowing time for the water to readjust, the pH can then be tested more reliably.