For a nano tank, not much rock I'm assuming. I actually have quite a few pieces in my fuge that are taking up too much room. Not a ton, but maybe two or three decent size pieces tops. I wouldn't ask more than 10 bucks or so for whatever I gave out, if that. PM me if interested. It's not rock I'm dying to get rid of, but, if it's helping out a fellow reefer, I'm cool with it.