ok here we go,
Protein skimming, also know as foam fractionation is a mechanical form of filtration. The idea behind protein skimming is fairly simply, many organic and inorganic substances(all that nasty stuff that collects in the collection cup) are naturally atracted to the interface between water and gas(air).
All a protein skimmer does is create a large interface area between air and water by producing all those little bubbles we see inside our skimmers when they are operating properly. The bubbles will rise naturally, with the atracted protiens attached to the microbubbles. The bubbles will rise to the top of the funnel and then burst releasing the liquid wastes into the collection cup. Some "studies have indicated that upto 80% of organics in an aquarium can be removed by an effiecient skimmer"(Dakin, 28). Skimmers can however have a negative effect when adding medacations to an aquarium because it will remove the majority of what is added to a tank.
KINDS OF PROTEIN SKIMMERS
There are three basic designs, the direct-current, counter-current and powered venturi skimmer. They all operate on the same ideas mentioned earlier, they just go about achieving the results differently. Some people believe one design is more effiecient than others, but that is something that I will adress later.
Direct Current- this is a basic skimmer design that involves and airstone placed inside a skimmer with the water from the aquarium passing over the bubbles in the same direction, this method however allows very little contact time for air bubbles and the water because the water and air bubbles are traveling in the same direction.
COUNTER-CURRENT- is similiar in design to the direct current except the water flows in the oposite direction of the airbubbles generated by the airstone, allowing a longer contact time, allowing more wastes to attach themselves.
Venturi Skimmer-
"Venturi air-injection was the next big technological development in the evolution of marine aquarium protein skimmers. A venturi is a specially designed piece of plumbing with a profile that resembles an inverted "T". Water is forced through at high velocity, which causes a low-pressure suction on the open stem (top) of the inverted T and draws air in. You may have noticed this feature on powerhead water pumps. In this application, venturis are used to inject air into their water stream to aid in oxygenation. In this application they are rather crude devices, but you get the picture. Protein skimmer venturi valves, however, are high precision instruments engineered to produce a very fine-sized air bubble. The better ones also come with a threaded needle control valve for fine-tuning the amount of air injected into the skimmer"(Steven Pro) I just used Steven's deffinition of Venturi, it was simple and illustrated the advantages of Venturi skimmer, and honestly I don't think I could do better.
Hopefully this helped with your understanding of what a skimmer is, how they work, and how essential they are to this hobby. I am also going to include a section in this post for people to post what skimmers they have used, and their experiences with them.
Brahm
oh yea and feel free to correct and add to these definitions
