im kinda new to all this water mixing stuff and plain and simple dont do it but i keep crystal reds, and oebt in tap water no ro unit here. i did have a berryed crystal red but kid decided the tank needed filled and use a part of a gallon of distilled and no more eggs but other than that all are great in tap water. i do not have a clue what my perameters are right now cause i have not owned a test kit in years but will be gettin one in a day or 2 so ill let any one who wants to know then. i do use miracle grow organic (peat based) capped with sand so that might have a bit to do with it. sorry for the randoms post but im just wondering what the gh/kh and all vs the ro water is about do most people have a prob with reg tap water so they cant keep caridina shrimp?