Re: use of a back ground?
It's personal choice, really. For my FW tanks, I am partial to a black background. For me, it keeps things clean by hiding filter hoses, etc.
There are photos of some rimless masterpieces in the forums that are breathtaking. Typically, they don't have a background. Intakes and outlets can be clear "lilly pipes" to reduce visibility. I've seen them mounted on the sides rather than the back to further reduce visibility.