does anyone has a suggestion, here's the scenerio, i have an existing 125 gal(reef) mostly SPS- and need to transfer entire stock to a 125 tall- i have about 2-3 inches of sugar sized substrate (sand), and the last time i did this I ended up losing alot of corals for i transfere everything in 2 days, so i believe what caused it was that the sand was stirred and the lower part became the upper part emitting some toxic gas. do you have any suggestion on doing this with minimal if not none casualty? how? and by the way, time is not of essence, i mean i can do the transfer if need be slowly. thanks