What Is an Aquarium Calcium Reactor For?

Simply put, a calcium reactor is a device used in a reef aquarium to maintain appropriate levels of calcium and alkalinity, or carbonate hardness, necessary for the growth of coral and invertebrates.

  1. How it Works

    • Carbon dioxide is pumped into a container holding some sort of calcareous material, like aragonite. Carbon dioxide's low pH causes it to break down before it is pumped back into the aquarium in the form of calcium and alkalinity.

    Where it Goes

    • Calcium reactors can be quite large and are normally placed in the cabinet below the aquarium. They can be placed on the cabinet's floor or in the sump.

    Using a pH Controller

    • Since the carbon dioxide has such a great effect on pH, many choose to use pH controllers in conjunction with calcium reactors. These devices turn the CO2 tank on or off if the pH in the aquarium gets too high or low.

    Advantages

    • The biggest advantage to using a calcium reactor is that, when properly set up and maintained, it can keep calcium and alkalinity at very precise levels. Although it may be a large initial investment, it is, in the long run, more economical than using the traditional two-part dosing method.

    Disadvantages

    • Calcium reactors are expensive, some run cas much as $1,500 or more. Without careful observation and modification, levels of pH and alkalinity can reach dangerous levels.