Ken,
i treated the 45 gal inclodung the 30 lbs i had in it quite some time ago. then changed out all of the water and always keep fresh carbon in it. i didn't find out until much later that the rock can absorb he copper. on that note however... i now have 160 lbs of rock in the 150 including the 30 that was copper treated. i have an anemone, cuke, tons of snails, crabs (which shouldn't be really affected anyway) and a serpant star all doing fine. i figured what little copper the 30 lbs may have absorbed would be quite diluted in the 150 gal. hmmm... ok now i need to go out and get a copper test kit...