sera guide - Marine aquariums

48 CO2 is only used in calcium reac- tors in marine aquariums. This device is usually placed in the sump and provides the aquarium with calcium hydrogen carbonate. The water inside the calcium reac- tor is acidified by the introduced CO2 and dissolves the calcium car- bonate inside the device. Soluble calcium hydrogen carbonate gets released as a reaction product. The amount of water taken up by the calcium reactor in the filter under- neath the aquarium (sump) is the same as the released amount. The CO2 supply for the calcium re- actor is best controlled by a pH con- troller such as the seramic pH Controller. The device interrupts the CO2 supply as soon as the adjusted pH value is reached. A pH value low- ered to at least 6.5 by CO2 is required for converting calcium carbonate into calcium hydrogen carbonate, for higher performance possibly a pH value lower than 6.0. This pH vale can be automatically maintained by the seramic pH Controller, provid- ed the pH measuring probe is locat- ed inside the calcium reactor.