How much muriatic acid do you add and how often to lower 260 alkalinity in 15000 gallon pool?

To lower alkalinity in a 15,000 gallon pool by 260, you would typically add about 3 quarts of muriatic acid. The frequency of adding muriatic acid to lower alkalinity depends on your current levels and how quickly they rise, usually every few days to a week. It's recommended to test your water regularly and adjust the treatment as needed.