I have a 125 with a Huma Huma and a Niger. The Huma Huma is always
pecking away at the rock and sifting sand. My live rock was pretty
much dessimated as the Huma Huma got to be a little larger.
Now I move rock in and out of the tank every couple months to give him
and the ecosystem some new material.
I have a couple rubbermaid tubs I "grow" rock in. I use a percentage
of my water change water to mantain about 40 lbs for each of my 2
tanks.
It has come in very handy when a tank has began to go south. And the
way the trigger cleans live rock it was either buy new rock every few
months or set up my tubs!
Good Luck