You will immediately have a working biological and mechanical filter for your hospital tank. This filter is a recent development, using sand as a bacteria settlement media. In a tubular design, sand is fully submerged in water. The water is pumped upwards through the sand, allowing bacteria to settle within. This filter provides a large surface for bacteria colonies, but sometimes lacks in providing enough oxygen for their performance.
Water is pulled through a mechanical filtration, using floss and insert cartridges.
They also provide enough space for chemical filtration media. The protein skimmer is a chemical filtration method. It takes out dissolved biological waste before it can decompose. This is achieved by a tubular design with air bubbles inside. The waste is attracted to the surface of air bubbles, which then rises to the water surface.