[ReefkeeperZ]

I've be chopping rocks up for years, because of fragging etc, unless the rock is big enough to be anaerobic inside you have no worries. you may lose some iner growing sponges tear a worm or two but it will be minor. If its anaerobic you may get a minuscule spike because of die of from oxygenating the previously unexposed area. but again that will be definitely a minority of rocks your smashing up. (i've literally split rocks in my DT with a cold chisel and hammer after lowering the water enough to get at them)