Ever walk on the beach isreal6655? If so, ever see foam on the sand, whipped up by the surf? This is the result of, and skimmers employ a chemical process called, "foam fractionation". Essentially, things one wants to remove are drawn to the surface of the bubbles, the bubbles rise and are "skimmed" off. Some would argue that what's being removed is actually coral food, which may be true, but, suffice to say that protein skimmers strip contaminates from the water, simply, and naturally. Very important piece of equipment. Next to the tank itself, and lighting, a very important piece of equipment in my book. You have only to look at what comes out of a skimmer to know you need one. Just my opinion.