What are the best rocks for malawi hap/peacock setup? I have cichlid substrate so I don't need rocks that help to buffer the ph. Mostly looking for something with mostly inert properties that stacks well and looks nice and is inexpensive. maybe something I can find at a landscape supply store. was thinking about making some terraces with some black slate rock. I put in that egg crate stuff underneath the substrate so I'm ready to rock. (so to speak)