Check the listing for details. Eheim Substrate Pro Filter Bio-Filtermedium Bio Filter Medium 1L 2 Bags Size New. Condition: New. Listed at 14.99 USD. Eheim Substrate Pro Filter Bio-Filtermedium Bio Filter Medium 1L 2 Bags Size New. Condition is new. The 2 bags are sealed. The box has some shelf wear. Eheim Substratpro Optimised bio-filter medium with perfect volume usage, long intervals between cleaning and top decomposition performance. Substratpro consists of pearl-shaped sintered glass. The spherical shape gives a high bulk density. Thus the whole of the volume in the filter (filter baskets or modules) can be utilised. Also the optimum surface of the beads provides intensive colonisation of the important purification bacteria. Due to the high number of bacteria, peak nitrite loads are more easily reduced and the maintenance intervals of the filter material are longer. Eheim Substratpro is suitable for fresh and marine water, is washable and can be reused. Optimised bio-filter medium made from sintered glass High bulk density due to spherical shape (beads) Very dense colonisation of bacteria Longer intervals between cleaning Better reduction of nitrite loads Reusable (rinse carefully to clean) Suitable for fresh and marine water Tip: Never clean or change all the filter media together in one operation (and never clean too rigorously). The bacteria cultures must not be completely destroyed, otherwise re-colonisation will be retarded.