Full sps reef, how to catch a powder blue?

[marie]

I've drained my 175g to catch all of my fish once. It took me 1.5 hrs start to finish and no corals were moved or damaged.
I have sand so I made a large hollow in the sand near the front of the tank and started draining the tank at the other end, ignoring the fish entirely. They were so used to me working on the tank that non of them were the least bit freaked out until they realized they were trapped in the hollow