A calcium reactor consists of a diffusion chamber filled with calcium carbonate and a low wattage circulation pump. The is an inlet to carry water from the aquarium into the diffusion chamber and a return outlet. The theory behind this system is that water is allowed to flow from the aquarium into the reactor,, Where it is circulated repeatedly over calcium carbonate granules. The idea is to retain the water for as long as possible in the diffusion chamber so that the calcium carbonate becomes soluble. But, at a ph of 8.2 or more calcium carbonate will not become soluble, so, carbon dioxide gas from a bottle is injected into the diffusion chamber at a slow rate. This creates an artificial atmosphere within the reactor unit and produces a localized drop in the ph level to around 6.0 and water at this ph can dissolve calcium carbonate to produce calcium bicarbonate. Because calcium bicarbonate is easily soluble it can be ingested by corals and other invertebrates for conversion back to calcium carbonate, an important substance for their skeletal and shell growth.The injection of carbon dioxide gas is carried out using an armature and reduction valve connected to a bubble counter. By adjusting the reduction valve you can count the bubbles and very accurately control the amount of co2 you administer. The flow rate of water through the reactor should be controlled exclusively from the inlet, and not the outlet. this stops any chance of a buildup of excess gasses within the reactor unit that could arrest the circulation of water through the pump housing. you can adjust the actual flow rate to allow a return to the aquarium of between 50 and 100 drops per minute. When this is coordinated with the input of gas through the bubble counter to be roughly the same rate, a maximum effect is achieved. Water returned to the aquarium can be expected to have values of 550 to 650 mg/litre calcium and a carbonate hardness of between 20 and 30 dkh.
