Pre bio or quick filter for connecting to pumps or external filters. The sera PrefiX Filter allows enhancing the filter volume of a connected filter by up to 1.6 liters (0.4 US gal.) with two variably useable filter baskets. The motorless filter is for instance suitable as a prefilter in case of cloudiness as a quick filter in case of pollution or as a biofilter for expanding the filter capacity of small external filters. The filter can be connected to a pump or an external filter by means of a sera hose 16/22 mm. Connecting several PrefiX filter in series is also possible. In case of fine grained filter media using the sera filter media bags 1 or 2 is recommended.