What is a protien skimmer, and what types are commonly used? Well you may know what a protein skimmer does by now but if not I will briefly explain a little. Pretty much your fish, inverts, and corals all .... well poo right? Algae also puts off organic waste. This poo and organic waste is referred to as detritus. So the most efficient way to remove the detritus from your system "tank" is to employ the use of a protein skimmer. How does a protein skimmer do this? Simple it mixes micro bubbles of air with the water inside the skimmer. The micro bubbles then bond with the detritus that is suspended in the water causing the detritus to rise to the collection cup and later be dumped out by you. Here are some of the main things that you need to consider when choosing a skimmer: 1. For the best skimming, the water flow through the skimmer should be pretty slow as to allow interactions of the micro bubbles and the detritus. The best designs for this are skimmers that employ water moving against the flow of bubbles. Such skimmers are called counter-current skimmers. 2. Make the skimmer reaction chamber as tall as possible to maximize the contact time that the water has with the air in the skimmer. If you are using a hang on or external skimmer you height is not limited as much as an in sump skimmer would limit you. Pump as much air into the reaction chamber as possible. The key to injecting air is twofold: a) maintaining the smallest sized air bubbles, and b) reducing any potential turbulence of the air bubbles in the skimmer reaction chamber. 3. The diameter of the skimmer can also be increased in proportion to the amount of water being skimmed. The larger the amount of water to skim, the wider the diameter of the skimmer should be. Types of skimmers Needle Wheel / Mesh Wheel: Also known as an aspirating skimmer, low to moderate water flow, good foam production, good bubble size, excellent contact time, cost-efficient, requires specialized impeller or needle wheel. Air driven counter-current: low water flow, good foam production (with new air stones), good bubble size, maximum contact times (with taller units), frequent maintenance and requires frequent water height adjustments (called tuning). Venturi: good water flow, good foam production, moderate contact time, requires a powerful pump, valve tends to clog. Beckett-head skimmer: high water flow, maximum bubble production, moderate contact time (swirling patterns will increase this), requires a very powerful pump, Beckett-head requires cleaning. Downdraftâ„¢: good water flow, excellent bubble production, excellent contact time. Units tend to be tall and bulky and require powerful pumps to create air bubbles. Recirculating: Recirculation can be added to the venturi and aspirating style skimmer design. The recirculation continues to fractionate the water inside the skimmer body to increase contact time and improve performance. These skimmers usually require an external feed pump to supply water to the skimmer, or they can be direct fed from the tank drain. For now this is just a basic description, we'll get into a more in depth discussion about skimmers as the thread progresses. Please feel free to ask questions or include any input you may have.