I'd just leave it fish-less for a while. Don't add medications or chemicals to the tank. You have plenty of good stuff living in there that you don't want affected by doing that.
Part of me is thinking of just tearing it down too, but then my xanthid crab wouldn't have a home. Guess I could put him in the hypothetical refugium I'm planning to build.
Doubt it'll be hard to wait. I have another tank that is older and never gives me problems that I am about to upgrade and start getting reef ready. So I'll have something to distract me.