I recently finished converting my 4 footer from a planted community tank into a rocky tang tank. Getting all the old sand out was a real pain but it paid off in the end. Substrate is crushed limestone, rocks are dead coral and the current inahbitants are a pair of adult Bristlenose's, a Pictus Catfish and five Julidochromis transcriptus. I'm getting more cichlids soon and I'll post more pics when I do.
Before
After
Julies
Before
After
Julies