EHEIM Karbon with net bag (fromerly EHFIKARBON) is ideal for use with initial set-up of aquarium in order to bind dissolved harmful substances. EHEIM Karbon with net bag is pH-neutral. Before use, wash with hot water and rinse several times under cold water. Suggested use: approx. 2 weeks. Suitable for fresh water only. Place the material into the filter on top of the layer of mechanical filter media. If medications are used, filtering must done through an newly-inserted EHFISYNTH layer. A practical net bag is contained in the packet.Do you have questions about this article ?