Reef Kalkwasser is a pure calcium hydroxide with features unsurpassed purity and solubility. Calcium hydroxide solutions used to prepare limewater (kalkwasser) that will maintain calcium concentrations at natural levels of sea water. Kalkwasser solutions maintain calcium directly and carbonate alkalinity indirectly. However, their ability to perform these functions depends on the evaporation rate and CO2 concentration. If these two factors are insufficient you can provide additional calcium with Reef Advantage Calcium, Calcium or Reef Complete Reef and carbonate alkalinity with Reef Builder or Reef Carbonate (Never mix these products directly to a solution of Kalkwasser). While Reef Kalkwasser is a high purity and is a mixture of lime water to prepare economic, the beginner, or someone with not much time to devote to your system, you can choose to use other less complex methods to maintain proper ionic concentration levels.