A protein skimmer is one of the most important pieces of filtration equipment in existence for marine aquariums, regardless of whether they are full-blown reef aquariums or simple fish tanks; indeed, a protein skimmer can in many cases be considered “life-support” equipment.  The waste exported by a protein skimmer helps maintain water quality at a level at which the fishes and invertebrates can survive and thrive.  Although many beginning hobbyists may scoff at the cost of a high-quality protein skimmer, they should take into consideration that the price of the skimmer and pump required to operate it pale in comparison to the amount of money they are likely to spend replacing sick and/or dead animals that passed as a result of poor water quality!  Well-seasoned, experienced aquarium hobbyists can sometimes maintain a system without a skimmer, but most of them will tell you that having a good skimmer makes keeping the system clean and healthy much easier!

A protein skimmer is in essence a reaction chamber in which a mixture of water and very fine bubbles are injected.  The bubbles have a weak electrical surface charge due to the orientation of the molecules that compose them.  The purpose of these bubbles is to adhere to dissolved and particulate organic matter in the water column (which come from fish and invertebrate waste, tap water, uneaten food, and many other sources, and which have an electrical surface charge opposite that of the bubbles) and remove it by forcing this material up through a column and into a waste receptacle, which is emptied as needed by the hobbyist.  Dissolved and particulate organic matter are a major source of the nutrients needed by microalgae (“hair algae”) and cyanobacteria (“slime algae”) to grow and reproduce, thereby covering every non-mobile object and animal in the aquarium in a sheet of waving hair or oily slime, respectively.  Elevated concentrations of latent organic matter in an aquarium are an indication of a poorly maintained system in which few desirable life forms will thrive.  So, the goal is to get these organics out of the water; this is why a protein skimmer is essential.