Turbos do a pretty good job on mine. I also have some brittle stars and a few small hermits that help out.
As for settlement on the bottom, theoretically, there should be enough flow in a BB tank to keep everything in suspension until it reaches the overflow, but I tweaked my flow to "herd" the really big/heavy particles (like tiny pieces of rock that may be chipped off) to a specific area that is sucked up in a water change. This is typically the only area that requires the vac, and only occasionally.