I found this old diagram of the Eco-Wheel filter on my computer today. One of the more different designs for an aquarium filter to come along in a while in many regards. <br /> <br /> The Eco-Wheel Filter <br /> <br /> I've seen one at a fish store on a display tank. It had the biggest PVC you've ever seen on an aquarium and one thing notable is the air-lift water return. And the wheel created a nice somewhat random surge in the aquarium. Although I did see some micro-bubbles. And speaking of the wheel, there was a light above it to encourage algae growth. A rotating algae scrubber of sorts. Here is an old thread: http://www.3reef.com/forums/product-review-archives/eco-wheel-32011.html Have you ever seen one of these in action?