Re: Viv Project
I would definately not advise replacing the bottom. You would have a difficult enough time making it watertight again with a glass bottom, let alone plexiglass (which doesnt adhere to glass).
Since the bottom is probably tempered, you could drill a hole near the bottom on one of the sides of the tank. Another option would be having an entirely self-containing system... Water doesn't need to be filtered much when there are plants in the tank.