Check out the Sandbed Swap article in this link.
<a href="http://fishwhisperer.homestead.com/articles.html" target="_blank">http://fishwhisperer.homestead.com/articles.html</a>
I followed it during my change-over a week and a half ago. It went pretty well. The key is to be prepared and plan everything out ahead of time. I would also suggest having your tubs for fish or corals set up well with heaters, powerheads, and even some type of light, in case you need to leave the livestock in there over a night or two. I chose not to rinse all of my new dry sand in order to save the fine sediments. This greatly compounded the problem of cloudy water. There was zero visibility for the first day and about 2-3 inches the next. I returned my live rocks, snails, brittle star, five mini hermit crabs, and conchs to the cloudy water the first night, but I left my corals in the tub until the end of the third day. I could just see the rock in the back of the tank after three full days. I had no fish to return as I lost the only two I had to a mistake during the swap. Other than that foul-up all of my corals and creatures survived. I had been warned to watch for a possible mini-cycle, but with my low bioload that never materialized. I still recommend testing your water every day following the swap and be prepared to change additional water if ammonia or nitrite begin to rise. My water now is crystal clear. I am glad I undertook the swap, but it is a lot of work and one very long day. Good luck.