My tank is medium stocked with coral. All softies and LPS. I dose about 15 to 20 ml per day of Brightwell's part A and B. Their part A has Mg too but recently my Mg was out of range high and calcium was where I wanted it, so I switched to Red Sea's calcium (no Mg) and it is more concentrated. I drove my Calcium up to 500 PPM before I realized it. You have to pick a brand and take some measurements as you go along. Then of course as the coral in the tank grows the dosing needs to change with it