not hard at all, get a large rubbermaid container or several 5gal buckets, syphon water out to fill the buckets half way, and take everything out of your tank. Be careful not to cover anything, squish anything or smother something that shrinks up on the rocks.

Then, take all, or most of your fish out, and put them into several containers. After this is done rework your rock and add everything back. Since I only have a 40gal, it was pretty easy for the two of us, took less than 2 hours.

MH