Made popular by European aquarium hobbyists, dosing kalkwasser has been a popular method of adding calcium to reef aquariums for decades. Eventually the American hobbyists caught on, but sought out other home-based products as the source of calcium hydroxide rather than stuff that was commercially available in Europe. These home use products include pickling lime for the most part, which is a food grade substance used to turn cucumbers into pickles. The art of pickling has gone way out of style these days, but the pickling lime is still available at your local grocery store from time to time. It especially pops up during the holidays when food essentially becomes the centers of our respective universes, so if you want to stock up on some inexpensive kalkwasser, grab you some pickling lime while it’s still around.