Kalkwasser is lime water with a natural balanced calcium/alk(reason for it's use in our systems along with the ability to aide in keeping PH levels up). Joe's Juice is simply lime+water only more pasty. I get my type 'S' at Home Depot in the concrete section. It's advised to use at your own risk as it's not a food grade and has a possibility of containing impurities. I've used it for a few years and haven't had any problems... my tank speaks for it's self.