PROBLEM TO BE SOLVED: To provide a method for easily injecting atmosphere to a circulating water while keeping the natural condition system in a new or existing aquarium at a required minimum budge and running cost; and to provide a device for injecting the atmosphere. SOLUTION: The method for injecting the atmosphere containing natural carbon dioxide and oxygen in the atmosphere comprises installing a device 13 for injecting the atmosphere, obtained by constituting a part 11 for mixing the atmosphere with the circulating water so as to be attached to a water pipe 2 of the device body, formed out of a light-semipermeable material to utilize the carbon dioxide and the oxygen in natural field from the atmosphere, in the midway of a returning pipe (hose) 15 of the circulating water of an external purifier 18, and injecting the atmosphere to the circulating water by utilizing the negative pressure at the sucking side under operation of a water-circulating pump 17. The installation cost, the maintenance cost and the electric cost can be reduced extremely because the negative pressure of the sucking side is utilized, and the method can cooperate with the environmental problem only by a very small amount because an artificial carbon dioxide whose influence on global warming as a greenhouse effect gas is worried about is not used. COPYRIGHT: (C)2006,JPO&NCIPI
