Gagné 2021, p. 34 (masses in grams, KH and GH in ppm CaCO₃; OCR reading checked by stoichiometric calculation)

Gagné tried only three of them and usually prefers the simplified Rao/Perger, which he could not tell apart in a blind tasting from the full Rao/Perger, easier to prepare and more convenient. With the Barista Hustle recipe, magnesium alone, he perceived clearly less sweetness every time, which is consistent with the common idea that calcium plays on the perception of sweetness, though no robust study has demonstrated it.

In 2018, in a blind tasting, he had already preferred Rao/Perger to Third Wave Water, judged too acidic, itself far superior to Montreal water. These recipes can be transposed to other hydrates, other volumes, other concentrations, to a non-distilled soft water or to other salts by simple stoichiometric considerations: ions can be added, never removed, so the starting water must contain less of each species than the target. This is what the calculator below does.

Gagné 2021, pp. 32-35; Gagné 2018, pp. 6 and 11-14