So I was talking to a guy at Capitol Aquarium in sacramento and he said they gravel vac their reef tank often. I have been suffering from a substantial build up of organic stuff in my sands and on live rocks, so I am considering this. I have heard people say not to do it in a reef, and now I have a guy telling me I definitely should. Do you guys gravel vac? Do you consider it necessary, optional, a bad thing to do? Why?