EHEIM coarse/fine filter pad for eXperience 150/250 Fine and coarse filter pads for mechanical and biological filtration. The porous material becomes evenly soaked with water and traps large and small dirt particles. After a short start-up period purification bacteria, which provide intensive biological decomposition of harmful substances, colonise the specially structured foam. The fine and coarse filter pads are reusable many times over. To clean them simply rinse and squeeze out, so that the bacteria cultures are not completely destroyed.