Reef Kalkwasser™ is a pure calcium hydroxide with unsurpassed purity and solubility characteristics. Calcium hydroxide is used to prepare limewater (kalkwasser) solutions that will maintain calcium concentrations at natural seawater levels. Kalkwasser solutions maintain calcium directly and carbonate alkalinity indirectly. However, its capacity to perform these functions is dependent on evaporation rate and CO2 concentration. If the these two factors are insufficient you can provide additional calcium with Reef Advantage Calcium™, Reef Complete™, or Reef Calcium™, and carbonate alkalinity with Reef Builder™ or Reef Carbonate™ (do not mix these directly with a kalkwasser solution). Avoid contact or breathing dust. Do not eat or get in eyes. In case of contact, flush area with water for 5-10 minutes. In case of eye contact, wash eyes with water immediately (5-10 minutes) and seek medical attention. Guaranteed Analysis: Calcium (Ca) 54.09%, [saturated kalkwasser: 0.09% Ca] DIRECTIONS: Never add this product directly to the tank. Add 3 g (1 teaspoon) to 4 L (1 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 gallon*). Drip this solution into tank. Monitor pH and carbonate alkalinity. Adjust rate of addition to maintain a stable pH (8.3-8.4). HINTS: Adding 4 L (1 gallon*) of a saturated kalkwasser solution to 150 L (40 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.