Mark Martin on Curing Live Rock
Mark Martin is the Blue Zoo Director of Marine Ornamental Research

It is necessary to cure almost all live rock (even if it was pre-cured), as there will always be some die-off of organisms living on the rock during transport. There are many ways to cure live rock, depending on the situation, it can take anywhere from several days to three weeks.  

To begin, fill a large plastic tub or garbage bin with pre-mixed and aged saltwater. Install a heater, a couple of powerheads and possibly an inexpensive mechanical filter of some sort. 

Because the live rock needs to be in warm, well-oxygenated water, heat the saltwater to 80 degrees F, and turn on the powerheads and filter (if installed). Add the live rock, making sure that it is entirely covered by saltwater. Cover the tub in order to eliminate light exposure while the rock is curing (this will help deter algae blooms).

After three days, test for ammonia. If the ammonia levels are still toxic, do a 50% water change.

At the end of one week, remove any obviously dead material from the surface of the rock (use a toothbrush or small scrub brush). Do a 100% water change.

Keep testing every three days until the ammonia level reaches zero.

Continue with 50% and 100% water changes until the rock is cured (no toxic ammonia levels). When the rock is cured, scrub off any dead material and place the rock in the tank.