The Aqua Medic midiflotor is an air driven counter current internal protein skimmer with an double-cylinder system for aquaria up to 400 litres content. It is characterized by the double reaction pipe that makes it a real counter-flow skimmer. The air bubbles rise in the inner pipe. Like an air lift, they take a high volume of water with them. This water is forced to flow downwards in the outer pipe. The air bubbles follow the water stream downwards until they reach the expansion cone. At this point, the air bubbles turn and rise in the counter-current upwards. This ensures a very high detention time of the bubbles in the water. A lime wood air diffuser producing very fine air bubbles is also included. In addition, the holding plate leaves space for a redox electrode. For the air supply, we recommend the Mistral 300 membrane air pump (not included).technical data Aqua Medic midiflotor:- diameter: approx. 57.5 cmlength: approx. 52 cm- total width: approx. 15 cm- Immersion depth: approx.