Although the aquacultured rock is a great idea, most of the time it is much more dense than the L/R that is more common. Some of the more ethical suppliers collect rock from hurricane or tsunami areas. Quite a bit of it has already been broken off of the reef. I have had L/R from Fiji, Tonga, as well as some of the Carib./Florida rock, Tonga area seems to be the lightest, most porous, which means you don't need as much of it as it has a larger surface area for bacteria to colonize.