Seachem 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 these two factors are insufficient you can provide additional calcium with Reef Complete, or Reef Calcium, and carbonate alkalinity with Reef Builder (do not mix these directly with a kalkwasser solution).
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.
NOTE: Many who use kalkwasser are quite successful with their marine systems and find it to be an effective way of maintaining calcium. However, it can be a difficult technique for the beginner to master. The carbonate alkalinity must be monitored and adjusted to ensure that it does not become depleted through chalk (calcium carbonate) precipitation. The magnesium concentration must also be monitored and maintained since precipitation of magnesium hydroxide (arising from excess hydroxyl ions) can lead to a change in the balance of the various buffer systems present which can result in drastic pH shifts.