Eheim's new superior biological media that improves and optimizes the performance of Ehfisubstrat. It is for highly active water purification with intensive biological decomposition of harmful substances. For use in all canister filters. Can be used in all applications like in any filter system, extra media for wet/dry sumps and in power filter media containers. It can also be used as a replacement media for the Eheim AquaBall. It is pH & KH neutral so it does not affect the water chemistry. It has a larger pore structure to ensure optimum bacterial colonization and delays the silting-up of the pores (for much longer intervals between cleaning).