Marine aquarium inhabitants produce waste substances, the quantity depends on the livestock and the feeding. By means of an effective skimming system, organic waste matter, the so-called DOCs (Dissolved Organic Carbons), can be removed. The DOC skimmer removes the compounds effectively from the water circuit, better than a bio-mechanical filter which means that by removing proteins "before" bacterial decomposition, crystal clear water is retained and a rise in nitrate and phosphate is reduced.