The limestone reactors operate according to the principle of the fluidized bed. They obtain high performance in combination with a special aggregate. Devices specially studied for easy interview and optimized operation in reef aquarophilia. The limestone aggregate being permanent motion thanks to the fluidized system allowing a contact surface between water and the aggregate much greater than in traditional reactors. The inverted circulation allows the use of a granulometry aggregate, thus offering a particularly large contact surface and a yield up to 50% higher than in a traditional reactor. The combination of the special drawing (patented) of the reactor and the principle of the fluidized bed offers large advantages: an optimal mixture of aggregate, water and C02 optimal contact surface of the Granuat self-purification, no accumulation of the aggregate, no formation of automatic degasment channels of the anti-return valve for probe group and gas collector dimensions: 280 x220 x 610 mm for Aquariums up to 2500 liters.