There is an attachment for the magfloats that allow you to add a razor blade to them. It does a terrific job removing coraline if used regularly (once a month in my case)
http://www.jlaquatics.com/product/cl...g+Magnets.html
I don't do anything to clean the rock or sand.
This is the same tank that I've had since 2006 so I really don't move things around much anymore. But if reaching through the back becomes too much of a nuisance later I can always cut an opening in the front and make up some doors.