CBBs are not a cure all! I would expect a well established 200g system is probably about the minimum - is that about right Larry?
To say a 200 is about the minimum would be a slight exaggeration but established in regard to water quality - yes. There are lots of caviots to getting things right with a CBB. If its put into a pack of wild or strong and established fish, it can cause the CBB to never feed normally as in Gary's case. That makes for a ton of work and expense to keep it alive. If you have two systems, that would be the greatest advantage. You can give it a nice large home by itself to heal its injured snout and get accustomed to you and frozen food and life in a tank. Most of the time they are extremely difficult to get started to eat on frozen foods and in this case having food in the water for them to look at is necessary. If its all taken by pigs that have been in the tank for a while, that stacks the deck seriously against the CBB. In a peaceful tank, they tame very nicely and will eat from your hand if they are not bullied or out raced to the food and will quickly become your favored fish. Once in great shape, then maybe they can compete in the main system, so long as there is plenty of space for everyone both day AND night. CBB's like many fish, like to find a cave sometimes that they can call their own. They need a lot of food top keep from emaciation, so a large tank with refugium and skimmer are your best bet. It could very well be around 200 gallons by the time you add it all together. There is always someone with an exception to the size issue, but those are very experienced reefers that also have a lot invested in equipment.