How to save ATS while treating DT with meds?

I'm thinking of running some treatment on the DT that isn't good for my ATS. The ATS is running off my refugium which I can isolate from the rest of the system by turning off some valves while the rests of the system is being treated. It would have to be isolated for 4 to 6 weeks.

Refugium is about 70 gallons. I don't actually have anything in the fuge except some liverocks and it isn't even being lit. Any problems with this? I'm thinking there would be little to no nutrient load in the fuge once it's disconnected to the system. I'd like to 'save' the ATS so that I don't have to kill of the screen and start from scratch.

thoughts?

I'll be running Vibrant which is said to kill off algae in the ATS

If you put a snail or fish in there, it should give some ammonia to keep it alive.