Protein skimmers or foam fractionators are readily available in every price range and are a basic necessity for any marine system. Beyond the requisite biological filtration, nothing is better at improving water quality than a protein skimmer.
The bulk of undesirable organic wastes that we want to eliminate from our systems and “surface active”, collecting near the surface of a gas-liquid interface. We can capitalize on this affinity in a column of aquarium water with air bubbles mixed in. Trapped materials, including wastes, uneaten food, and more, rise and are collected at the top as foam.
The tools that accomplish this are called foam separators, fractionators, air-strippers, or protein skimmers. (They actually remove much more than proteins, and purists tend to refer to them as foam fractionators, although the term protein skimmers is deeply entrenched in the aquarium lexicon.) Whatever they are called, the action is the same, with complex organic substances attaching to tiny air bubbles rising in a column or chamber. A dark, waste-laden foam concentrates at the top of the unit to be separated from the water and collected for disposal.
Types of skimmers:
Protein skimmers generally fall into four types: air-driven, venturi, downdraft, and "other".Air-driven protein skimmers use a wooden or glass air stone to produce bubbles in a column of water. In hobbyist terms, we usually call these guys counter current skimmers. At one point co-current and counter-current was a big debate. These terms refer to the rotation of the water inside the skimmer. I don't think anyone cares too much about this debate anymore. Air driven skimmers require periodic (monthly) replacement of the air stones, a strong air pump to drive the air stones, and a small water pump to move water in and out of the skimmer.
See our full line of protein skimmers