Abstract
The water quality, the scale of the aquarium system and some relating factors were investigated on commercial aquariums equipped with closed-circulating system. The data were analyzed mainly for the discussion of nitrate accumulation caused by fish metabolism and excretion, N/P ratio and others, in comparison with natural waters. Meanwhile, the purifying activity of the filter sand was estimated on the basis of the balanced-aquarium theory by SAEKI and his fish culture experiments.
By using these results, the methods of calculating the amount of sand filter which corresponds to the amount of fish, the amount of supplying water required to prevent nitrate accumulation, and the rate of aeration to total oxygen consumption of cultured fishes were compositively calculated.
From these analyses, the necessary basic standard for planning the installation of an aquarium was determined.
