Beth, the skimmer is very compact and can be easily hung on either the back of the tank or the side of the sump. The one I have is hanging on the back of the sump. As far as noisy, the water does splash (waterfall) back into the sump. This makes, what I consider, a pleasing running-river-like sound. I think it's rather soothing and relaxing. With this I don't have to spend extra money to buy one of those "nature" sound devices. Other than that sound (noise), I would totally disagree that it's noisy.
The following info is provided as part of the manual by the manufaturer. I went ahead and typed it verbatim (especially for you, beth). It reads: "AquaC skimmers inject water through a specially engineered port designed to create a powerful air-induction spray. As this spray bombards the water within the skimmer's main chamber, thousands of bubbles are formed and allowed to react with unwanted proteins and waste. After the bubbles become coated with organic wastes, they rise up the foam tower and spill into the collection cup. Unlike traditional venturi or air-stone skimmers, your AquaC High Performance Skimmer processes aquarium waste with maximun efficiency."
I hope this helps....
