Was wondering what all of you use as a background? I want a black BG but not the one that just sits behind the tank. Can I use black contact paper ? the ones they use to cover school books ?
You could always use matt black spray paint. It'd be on the outside (as opposed to the inside which I think you're wanting to do?), but it would be perfect contact so no air bubbles if that's the thing you were worrying about?
Another option for flat black is simply to tape on black construction paper. You would need to be careful not to get it wet but it looks pretty good as a simple background.