Sorry. I am pretty bad at math.
Can you explain where the full recipe is found?
Where does it say 610mL?
I always assumed the part 1 (alk), part 2 (ca), and part 3 (mg) each had a solution of a gallon. Where you add equal parts of a gallon. I assumed a gallon of alk solution used will require 1/3 a gallon of mg.
3. Using both Epsom salts and
MAG flake, dissolve 7¼ cups
MAG flake and ¾ cup Epsom salts in one gallon of water, and use that to supplement magnesium in amounts determined using this
linked online calculator, with the entry "Randy's Recipes 1 and 2 Versions A and B," and ignore for this purpose what those designations mean. This recipe is preferred, but its advantage over recipe #2 is minimal in most cases.