i rarely move the big rocks. i use a powerhead to blow the crap out of the rocks then vaccuum it up. maybe once a year ill pick up most of the rock and move it around... but its stable the way it is and i dont want to move it.
I have alot of pink quartz for my rock structure in my 125g. When I do my water changes, I vacuum one side of the tank, then just restack the rock on the other side of the tank. I also have to move the sponge/power head from the same side and build the rock structure around it again. That's the pain in the ass, restacking rocks is no big deal. Fish seem to enjoy hanging out on the other side of the tank for a couple of weeks. I do a 50% WC every week but only move the rocks every other WC.
I broke any tank over 100 gallons into thirds. So each water change I would move 1/3 or the rocks. It worked out fairly well. Just got hard when I got my 3 ft tall tank. (I don't keep much rocks in my tanks now since my fish would hurt themselves too much.)
