i use rock from beaches i collected they dun seem to be real live rock that are purchase but it seem ok for my tank without any problem but look out for small crab that hide inside the rock they sometime do attack fishes, i washes my rock with fresh water 1st then into my tank that is cycling, now been almost 6 month.
make sure look out for sand rock they are very beautiful with hole in the middle
and some many hole my fish love swim through and fro them