If the stuff is still free floating around the tank, aggressive mechanical filtration will remove it. So if you have a free filter laying around, put some filter pads in it and let it run.
If you are planning on replacing 100% of the water anyway, I wouldn't worry too much about this problem. You could always take out the LR
and wash it off with freshly made SW
as well when you empty the tank. That would ensure the rocks are free from the "mirror coating".
I am getting my RO/DI unit tomorrow. Anyway, I was planning to replace the water once I get it. I am going to empty the tank completely and put fresh ro/di water. Is it ok to do this while live rock and sand in place?
I am assuming you are going to mix up the sw
BEFORE you put it into the tank with the LR
. In other words, you aren't planning on putting in 100% FW
into the tank with your LR
and then add the salt? Just want to make sure we are on the same page.