A protein skimmer is a form of mechanical filtration used on saltwater aquariums. The foam is forced up

the neck of the protein skimmer isolating the waste in separate collection chamber. The water exiting the

protein skimmer is striped of a large portion of the dissolved organic compounds that it contained when first

entering the skimmer. The most beneficial use of a protein skimmer is on a reef tank or

invertebrate aquarium. A more appropriate name for a protein skimmer is "foam fractionators," due to the

fact that the bubble concentrations (foam) serve to separate (fractionate) dissolved material from the water. 

A protein skimmer is also helpful when it comes to algae control. What actually happens when you run the

protein skimmer is that it creates a huge column of bubbling water within the tank. Protein Skimmer is one

of the most important pieces of filtration equipment invented for tropical fish aquariums, whether you have a

coral reef aquarium or just a fish only tank. The protein skimmer is technically not a “protein skimmer”

because it removes more then proteins, and the water is not just skimmed on the surface. 

The problem is even the very best skimmers do not remove all of the organic matter and do not remove

nitrates at all and nitrates will still increase. The difference between brands of skimmers is most evident

in the ways they move water and generate bubbles. Another key difference in protein skimming is the

size of the waste particles.  Also, select an air driven, venture, or down draft design based on the size of

the aquarium, system design, and the type of animals you're going to keep.  Bubble size and contact time

determine how effective and how fast a skimmer will work.  The most important recommendation is

that you find one that is matched to the size of your system.