Ya I've been thinking about how much of a pain it would be to have one under my tank, with the opening being so small. I just really need room for more light. I can't afford anything but CF, and they don't come as compact as MH can.
I would love to upgrade, but I don't have the money or the space, right now. My little boy and I live in a small two bedroom apartment, and I'm in college right now. I will probably have to move in about two years, to a bigger school, and I won't have the means to move my tank. I figure I will upgrade when I settle somewhere, and hopefully get rich! lol
So, why do I need the bio-wheel? It came with the tank so I've just always used it. I thought about getting a small hang on refugium. Foster and Smith has one that is only 7.75 x 4 x 7.5. I just don't understand how they work, of course.