Mikell, I believe you meant to say calcitic limestone or oyster shell, dolomite is lime. Just so folks aren't confused. My RO produces water that gives a reading of 0, whether the meters can accurately measure at that level is questionable, although that is with various meters. That is with a hydro logic unit, when I used specta pure the readings were around 20ppm. I find using a remineralizing ro unit is a much simpler choice and cheaper in the long run as opposed to bottled cal/mg. A great filter is the MineralPRO.
