DNWB line of Reef Octopus protein skimmers is a popular design that works by a special wheel inside the skimmer pump which chops the air and water into fine micro bubbles. These recirculating protein skimmers can be installed in sump or as a free standing units. Special needle wheel produces more micro bubbles which highly increases the skimming ability compared to our competitor’s models. Simple to use! Plug it in and set the water level using the precision wedge pipe.