| 摘要 |
<p>An aquarium filter assembly comprises a casing with perforated side walls and a filter tube inside the casing surrounded by a filter block of porous plastics foam; the filter tube has an additional lateral branch for recycling filtered water. This branch may be used either for fixing the filter tube inside the perforated casing, the branch being pushed into a hole in the casing; or for fixing the filter tube together with surrounding filter block outside the perforated casing, in which case the branch is inserted into a corresp. hole in a casing with closed side walls but open bottom which can be pushed back into the perforated casing. The latter method can be used when it is desired to place peat or other slightly acid material in the perforated casing to rectify the acidity of the water.</p> |
