In my opinion I would go with the fish being treated separately and leaving your main tank alone for at least 6 weeks. Doing hypo in a smaller tnak would be alot easier than doing it in a 150 gallon tank! And then theres corals, inverts and other creatures that you might have in there.
Just my 2 cents, looking for the easiest solution for ya.
180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18