thanks for the addvice, iam not sure how i will approch the task,does anyone have a step by step, maybe something like this, Get 2 larges tub--big enough to hold all the rock comfortably, about 1/4 of the water in one, another 1/4 of the water and the fish in the second. Home Depot, WalMart, Lowes, Target--all have heavy duty rubbermaid tubs for less than $10 that will work just fine for temporary use.
Drain water into both tubs--less in the one for the rock. Remove everything, then topoff the rock tank so everything stays covered. Put a towel or sheet over the tub with the fish to prevent jumpers.
Remove all the crushed coral (a clean dust pan works very well). Sort through as you pull it out for snails and worms. Keep the top layer of CC--put it in nylon bags to help seed the new sand bed.
Add the sand, and any base rock. Put a large plate on the sand, and start pouring new water into the tank. The plate will prevent the sand from being too stirred up. Get enough water in to turn on the heater--about half. Start adding the live rock back in, top off. Bring up to temp. Return livestock to the tank. Stash the nylon bags in the tank for a few weeks, removing incrementally as the sand bed develops. any thoughts?