PURPOSE: To realize the large capacity circulating aeration of a deep water layer by providing an air chamber to the lower parts of a plurality of intermittent air lift water pumping-up cylinders and arranging an air diffusion plate thereto to form a lower water pumping-up device and providing a lateral guide device to the upper part of the lower water pumping-up device.

CONSTITUTION: This large capacity deep water aeration device is arranged in a deep water lake 22 to be supported vertically between an upper float chamber 20 and a lower wt. The compressed air sent into an air chamber 3 from a hose 16 is discharged into a distribution cylinder 2 in a group to form an air bubble ball 29 in the distribution cylinder 2. The compressed air sent into an air diffusion pipe 4 and an air diffusing plate 5 from air sending hoses 14, 15 is discharged into water as fine air bubbles 32, 33. The air bubble ball 29 and the fine air bubbles 32, 33 rise to collide with a truncated cone 7 having a lateral guide 21 to rise through a communication cylinder 12 as an air bubble ball 37 and discharged into an outer cylinder 17. By this constitution, separate circulating streams are generated in water by lower pumping-up and upper pumping-up to generate convections in two upper and lower stages.