I have been meaning to ask you how that worked out for you. I just have the background roll taped behind mine and I don't really like it. But I'm not sure if I could paint mine because I only have a few inches clearance between the tank and wall.
The Plasti dip worked great. Painted it before I moved it inside obviously. The good thing about that is if I ever want to get rid of it I can just peel it off!
I change my mind all the time, lol, so i switch between pieces of fabric or dollar store table cloths taped to the back of the tank. Quick and easy to change colors that way! I scrape the sides and front. I used to scrape the back but got tired of hitting corals. Currently i superglued a couple pieces of green star polyps to the back glass hoping it will cover it.
i always let the coraline grow on the back glass. i may change my mind on the new tank i will be starting very soon though. i'm thinking about doing the pond foam thing and aquascaping much of the back glass. not sure yet though.