Sand is my favorite substrate (besides bare bottom). All you need is a siphon and pass about 1" above the sand and it'll suck up all the detritus without an issue.
A black background would be a big improvement as well. Not only does it help fish with being less stressed, but it really makes their colors pop as well. On most of my tanks I've just taped a black trash bag to the back, but with some I have spray painted it and you can't really notice a difference between the two other than one is glossy and the other is matte.
I really like the idea of dividing it, but why did you?