Coarse Foam for Compact+ 2000, 2000, and 5000. Includes 2 pieces. Specially structured materials provide outstanding purification wherein the water permeates them evenly, and coarse particle residues as well as even the finest particle residues are trapped mechanically. After a short run-in period purification bacteria lodge in the special foam material and ensure the intensive, biological decomposition of toxins. Carbon pads have an adsorptive effect as they dissolve pollutants trapped on their surface and thereby removed from the water cycle.