Kalkwasser Reactors

What is kalkwasser? Kalkwasser, or limewater, is a calcium hydroxide solution that supplements a reef tank with calcium and alkalinity. A kalkwasser reactor is an automated kalkwasser dosing solution. The Kalk reactor is partially filled with calcium hydroxide powder. A pump (or stirrer) periodically disturbs the media to saturate the water with a solution that is rich in calcium and alkalinity.

A kalkwasser reactor connects to an auto top off system (ATO). As tank water evaporates, the ATO delivers freshwater into the Kalk reactor. Then, kalkwasser slowly flows into the tank, replenishing evaporated water while raising calcium and alkalinity. Kalkwasser (pH 12) helps raise aquarium pH, unlike calcium reactors, which tend to lower pH. Some hobbyists use both a Kalk and Ca reactor to maintain high pH.