Keep your tank water pure and clean with Eheim bioMECH Mechanical Pre-Filter Media! Designed for use with freshwater or saltwater aquarium filters, it attracts colonization for cleaning bacteria to remain. This results in biological water purification that contains no water hardeners. Washable and reusable, gently rinse to ensure bacterial cultures do not get destroyed. Created for simultaneous mechanical and biological water purification, this pre-filter media is crafted from pH-neutral material to help stop dirt particles from re-entering your aquarium, leaving it cleaner and clearer. This is also great for use with Aquatic Turtles, Aquatic Amphibians, and Invertebrates.