Kalk+2 is intended for use by experienced hobbyists who are familiar with kalkwasser (calcium hydroxide-based) products. The calcium concentration (”[Ca2+]”) and pH in the aquarium should be determined by using an accurate test kit prior to supplementing. Do not add this product directly to an aquarium without diluting in water as directed, and do not overdose; it must be added in a controlled fashion with a dosing device. Create a stock solution by dissolving 6 grams (~1 tsp) of Kalk+2 in 1 US-gallon of fresh water (preferably purified) and allowing at least one hour for any settling to occur; each ml of the saturated sol’n will increase the [Ca2+] in 1 US-gallon (3.785 L) of water by 2.3 ppm, strontium concentration by 0.04 ppm, and magnesium concentration by 0.06 ppm. This solution must then be dosed/dripped into the aquarium at such a rate that salinity does not fall below 1.021 g/cm3 and pH does not increase by more than 0.1 every hour, nor is it ever allowed to exceed a value of 8.5.