Calculate the volume of water in your tank system. Measure the alkalinity to calculate the amount of calcium carbonate required. One measuring spoon of Bio-Calcium Actif per 26 gallons raises the alkalinity by 1.5 dKH and the calcium content by 10 mg/l. Tropic Marin recommends an alkalinity level no greater than 9 dKH. Sprinkle Bio-Calcium Actif onto the surface of the water in a place with a strong current, preferably in the filter sump, making sure that no undissolved crystals come into contact with the inhabitants. The maximum recommended dose is two measuring spoons per 26 gallons of aquarium water per day.