I've always been less than thrilled with using Kalk. Holdover from when people only used vinegar to clean pumps. The calcium deposits would build up on my pumps and the vinegar would damage the motors by penetrating the plastic and corroding the magnets inside.
What two part are you planning on using, or are you going to go with Kalk? Nothing wrong with Kalk, you just need to clean your pumps with either muriatic acid or citric acid.
Reefbreeders also sells dosing pumps as another thing to consider.