Patent ID: 7273547

Claim:
An outside-type filtering apparatus, comprising a filter device detachably supported in an externally hitched manner on a wall surface of an aquarium, and a water pump for pumping water stored in the aquarium into said filter device, said filter device includes a filter case defining a filtering chamber having an unpurified water chamber nested within a purified water chamber, the purified water chamber being in direct communication with the aquarium via a drain pipe, the drain pipe being detachably mounted in said filter case and including a sidewall and an inlet defined at a first end and a drain port defined at a second end, the inlet being defined in a first portion of the sidewall, facing a filter element and being in direct communication with the purified water chamber, the sidewall directly contacting the filter element to define a partition wall therebetween which isolates the filtering chamber and the drain pipe relative to each other in a water tight manner, and the drain port including a nose portion extending along a water-flow wall of the filter case and being in direct communication with the aquarium, wherein the water pumped from said water pump is stored in said filter device, and the stored water is filtered through the filter element by the depressurization of the inside of the filtering chamber caused by a siphon effect, and the filtered water is then returned into the aquarium.