The Calciumreactor KR 5000 supplies dissolved calcium to reef aquaria up to 1,250 gal. Similar to our smaller models, it is designed as a closed system. An integral pump provides internal water circulation. A PG 13.5 threaded port accepts an electrode for measuring and controlling the pH within the vessel. The reactor has a volume of 8 gal., and is supplied with a 44 lbs bucket of hydrocarbonate.