The problem here is that this is not an empirically solvable problem, and there are (in general) infinite possible solutions, depending on what you stock. Which solution you choose depends on what you believe to be most important (i.e. you have to trade off being a little low in one category...

It seems very clunky to me to have the water calculators entirely separate from the recipe wizard. These should definitely be integrated. This also has the benefit of live updating estimated ph and filling in minerals.