This might sound really silly. I have 2 WTFs that are almost one year old. They are in a modified tank. I started with a 20 gallon long and on top, added another tank that covers about half of the tank and adds about another 12 inches of height. What I would like to do is portion off about 1/3 of the bottom, add a filter/waterfall and throw a few tetras in the water. Has anyone done something like this? If so, what are some things you learned and would do differently? Any cautionary tales?