Never add this product directly to the tank. Add 3 g (1 teaspoon) to 4 L (1 US gallon) of water and mix to dissolve. If using pure water, a fully saturated solution is prepared by adding 6 g (2 teaspoons) to 4 L (1 US gallon). Drip this solution into tank. Monitor pH and carbonate alkalinity. Adjust rate of addition to maintain a stable pH (8.3–8.4). Notes: Adding 4 L (1 US gallon) of a saturated kalkwasser solution to 150 L (40 US gallons) will raise calcium by 24 mg/L. Always use the clear supernatant (top solution) only and do not allow undissolved material to enter the aquarium. Keep this container tightly closed when not in use and minimize solution/air contact to avoid calcium carbonate formation/precipitation.