The Calciumreactor is a closed system designed for universal use. It can be used as a bypass system, independent from the water level in the aquarium or the filter sump. Its characteristics are the big volume ( app 10 kg Hydro-carbonate) and the integrated circulation pump. By addition of CO2 , the pH value in the Calciumreactor drops and Hydro-carbonate is dissolved. In spite of the slow flow rate of 1 -4 l/hr ( 0,25 - 1 gph) big amounts of dissolved Calcium get into the aquarium and can be taken up by the animals. The Calciumreactor is supplied with a port for the CO2 probe (Standard thread PG 13,5).