Adding sand after the fact question

[fishoholic]

So I have a 80g refugium tank and I decided I want to now add a sand bottom. I'm thinking I should remove my lionfish before adding the sand. Problem is he's harder to catch then I thought. I will remove the rock to catch him if needed though. Also a bit worried about getting food to him in the reef tank but he's used to the feeding stick and my other fish in that tank prefer mysis over the krill so I don't think they'd steal his food.

Has anyone added a new sand bed to an established tank with fish in it? Where the fish ok during the sand storm? I figure sand storms happen in the wild but obviously my tank is way more contained then the wild, which probably makes a big difference.

I'm kinda thinking the sand would take to much oxygen out of the water once it's added, so I really should remove the lionfish first. But I thought I'd ask and see what others think. I am rising the sand thoroughly first before adding it. Also thinking I should try to suck up some of the detritus on the bottom of the tank before adding the sand, or does it matter?