Protein skimming (aka foam fractionating) is one of the most important methods of filtration for a marine aquarium, whether it be a coral reef tank or a fish only tank. The waste extracted by a protein skimmer helps in maintaining water quality at a level that corals, fish and invertibrates can survive. A protein skimmer is a vessel in which a water flow is injected with tiny air bubbles. The bubbles have a weak electrical surface charge. The small bubbles adhere to dissolved and particulate organic matter. This foams up a column and overflows into a collection cup. The taller the column the longer the particulate matter has to adhere to the small bubbles. Dissolved and perticulate organic matter are a major source of the nutrients needed by undesirable micro algaes (hair algae) and cyanobacteria (slime algae). Select a model that meets or exceeds your needs.