haha depends on the type of scaping, can see that all the dirt are gathered in two areas haha. u can try experimenting by adding a powerhead and see it the dirt will settle at the corner of the tank. you got large caves making it easier to work with, can play with the water current
my scaping was quite different from yours. the base of my rock work is dense (very little gap) made up of big rocks, so quite unreachable. even if i add a powerhead, the dirt will just get blown into another crack or hole some where..... i could only clear particles that settle outside.