Using the softest water possible is important for the longevity of StarSan solution. As mentioned, the cloudiness is caused by the complexing of the active ingredients with the calcium in the water. While the cloudiness does not indicate the solution is ineffective, the cloudiness is a precipitate and it does coat all of your equipment soaking in the solution with a slimey layer. In my opinion, that is more than enough reason to insist on using completely softened water. Distilled, RO, or ion-exchange softened waters are OK for making up StarSan solutions. Be aware that you may need to add more concentrate when using a softened water since there is probably a good bit of alkalinity in that water that neutralizes some of the acid.