Lately, everybody has been all high on DSB's for their ability to remove nitrogen from the tank. Does live rock not accomplish the same purpose in that its deeper zones are anaerobic and encourage production of N2 from nitrate. The reason I ask is because at this point, it would be very difficult for me to add fine sand to my tank unless I remove the 1000 lbs of live rock and all the corals attached to it. Does the large volume of rock not do the same thing? I do have about 3 or 4" of coarse coral sand under my rocks in my home tank.