EHEIM Karbon (fromerly EHFIKARBON) is ideal for use with initial set-up of aquarium in order to bind dissolved harmful substances. EHEIM Karbon 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.Do you have questions about this article ?