Have a 25% SW
change ready to go. I'd put the fish and rocks in separate containers with a small PH to maintain oxygen.
Prolly gonna have to remove rocks to catch the fish anyway. I have heard of bad water issues from stirring around the sand, but I didn't have any problems.
That 2 hours will not allow for the dust to settle, so it might take a bit longer.
I'd also plan on acclimating (just like a new fish purchase IMO
) the fish and inverts before they go back in - assuming you did the PWC
after the rocks were re'scaped.
Also, don't limit yourself to adding only one shelf for one coral. Do more.
I'd also consider a new toothbrush and scrubbing the rock in the tank it's already in. That way, when you do the water change you can suck a lot of that stuff up with the dirty water.
How's your phosphate readings. Could be a reason for the algae.