External biological aquarium filter
Patent 4265751 Issued on May 5, 1981. Estimated Expiration Date: 
September 21, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
September 21, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2729337 2935199 3321082 3324829 3441145 3485373 3554375 3785494 3835813 Filter with an open-cell elastomeric foam InventorApplicationNo. 06/077660 filed on 09/21/1979US Classes:210/232, WITH REPAIR OR ASSEMBLING MEANS210/416.2, For aquarium or swimming pool210/451, Internal fixed shoulder supporting filter elementD23/209Filter or strainer (2)ExaminersPrimary: Adee, JohnAttorney, Agent or FirmInternational ClassesA01K 63/04 (20060101)B01D 29/01 (20060101) B01D 29/00 (20060101) AbstractAn external aquarium filter is disclosed, the filter including a filter receptacle having a filter chamber for receiving contaminated aquarium water and having a clean water chamber. The two chambers are separated by a filter bed, with the clean water chamber being located above the filter chamber, whereby the flow of water is upwardly through the filter bed. A siphon input tube supplies the aquarium water to the filter chamber, and an output conduit supplies the clean water from the clean water chamber back to the aquarium tank. A commercially available aquarium air pump provides compressed air into the output conduit in order to airlift the clean water from the siphon level into the aquarium tank. The filter bed can include a layer of open cell reticulated foam plastic material, such as polyurethane foam, and a layer of activated carbon. | |
