ppm HCO₃⁻ per ppm alkalinity-as-CaCO₃: 61.016 / 50.043 = 1.21927.
This is exact only when all of the alkalinity is bicarbonate, which holds
below about pH 8.3, so for almost every brewing water. Above that, carbonate
starts to matter and the two entry forms give different answers.
ppm HCO₃⁻ per ppm alkalinity-as-CaCO₃:
61.016 / 50.043 = 1.21927.This is exact only when all of the alkalinity is bicarbonate, which holds below about pH 8.3, so for almost every brewing water. Above that, carbonate starts to matter and the two entry forms give different answers.