I had the same problem with a fine sediment on the sides of my carboys, even the smooth ones (i.e. those wilhout ribs). I read on here where the way to get rid of that was to swivel the carboy side to side and the sediment would drop. This is a good idea, but somewhat difficult to do so I made a tool to assist myself.
I bought a 6" turntable bearing at Home Depot for $4.49, cut out two 12' x 12" pieces of 3/4" plywood and attached them to the turntable bearing. The bearing has a 500 pound capacity. It works like a charm.