| 摘要 |
PROBLEM TO BE SOLVED: To make water nearly uniformly flow over a wide range in a gravel layer with low resistance, thereby improve the filtration efficiency and remarkably reduce the maintenance frequency in base filtration equipment provided with a water absorbent having water suction ports and a drain port, embedded in the gravel layer at the bottom of a water tank and having water absorbent passages formed in the interior thereof, a suction pipe connected to the drain port and extending in the vertical directions in the water tank and a pump connected to the suction pipe and capable of circulating water in the water tank successively through the gravel layer, water absorbent and suction pipe. SOLUTION: This base filtration equipment comprises the water absorbent K formed into a flat box shape covering the base Vb of the water tank over the nearly whole surface of the base Vb of the water tank, a plurality of grooved water passages G1 and G2 of the V-shaped cross section formed on the top surface of an upper wall part 4a of the water absorbent K and a plurality of small holes 1 to be the water suction ports bored at the bottom of the grooved water passages G1 and G2 so as to distribute over the nearly whole surface of the top surface of the upper wall part 4a.
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