Originally Posted by Innovator
If you previously cycled your tank then any new rock would need to be cured because the die-off will recycle. At this point siphon any die-off from the newly placed rock and perform 50% water changes daily if possible. Do you have livestock such as fish, coral, or other invertebrates?
I agree with Innovator here, but you can do some more. When you do the water change save the water in a bucket. Put the LR
one at a time into the bucket and scrub the dead off it with a new toothbrush. Don't worry about hitchhikers they will be fine as long as you use the salt water. Replace the scrubbed piece in the tank and go on to the next. This will remove dead cells on the rock and the cycle will be much smaller.
Or just wait it out and do the full cycle. If you have life in the tank by all means scrub it or better yet cycle the new rock separately in a bucket with heater, pump and water from your tank.