The Kalkwasser reactor/stirrer doses a mix of Calcium Hydroxide and water into the aquarium. The dose usually enters the aquarium in place of or in conjunction with your top off water. The amount of Kalkwasser you can add to the aquarium will depend on the amount of evaporation you aquarium looses. If demand for CA/Alk is greater than the amount of Kalkwasser solution that can be added to replace evaporated water this may not be the best solution. Kalkwasser will also push pH up slightly due to its very high Alkalinity and pH. This maybe advantageous if your aquarium suffers from low pH, or you use it in conjunction with a calcium reactor as the use of a Calcium reactor can pull pH down slightly.

 

Calcium reactors are filled with hard calcium carbonate media, CO2 is added to the reactor and as CO2 is an acidic gas this pulls the pH down within the reactor. The low pH environment then causes the Calcium carbonate to 'melt' and liberate a balanced concentrate of Calcium and Alkalinity into the effluent. The effluent that leaves the reactor will have a suppressed pH due to the low pH conditions required inside the reactor so the reactor is best set up to run during hours of lights on when the natural pH of the aquarium will be higher.