I cured my rock in my tank without any problems, but I can almost guarantee you'll get some responses that strongly advise against it. I guess it probably depends on how much die off you're going to have on the rock. If there's a bunch of dead stuff on the rock, I'd scrub all that off at the very least. The secret seems to be good skimming and lots of water changes. Keep your protein skimmer going 24/7. I actually didn't do water changes when I cured mine, but I think it led to algae problems later and that was with only about 15-20 lbs of rock initially. One other option you may have if you're getting your rock from a LFS is they may be able to keep it in their curing tank for you. That's what mine does. I pay for it, he tags it, and I come back in a few weeks when it's cured.