I use Randy Holmes-Farley method of reef supplementation. I use calcium carbonate (prestone driveway snow melt) for Ca dosing, bicarbonate (Arm & Hammer Baking soda) for Alk dosing, magnesium (Espson Salt) for Mg dosing.
I dose at the Ca & Alk @ 5ml/hr.
I'm planning to giving a presentation on this method in a discussion group at the end of May in my office. I will be making an announcement in the next week or so If interested .