Are you thinking a few hours for a tank change/move or storage? When I upgraded my 30 to a 90, my existing rock was taken out and added to new bins of temp controlled saltwater. All bins had fans and heaters. It was this way for about 12 hours until I got the new tank/stand delivered and set up.
Once its starts to dry off, thats when your in trouble. Grab a wet towel and lay it over the top of the rocks while your doing what your doing, to help keep it from drying out.