In regards to copper treatment, just bare this in mind:
If you leave them in that tank for a long period of time before treating them with copper, ich can fall off and cyst itself onto the glass of the tank. If you treat for the recommended two weeks then remove the copper, that ich can 'live' and reinfect your fish.
Do water changes with copper dosed water at the same level as the tank to maintain medical effectiveness of copper.
That being said, ammonia in a tank that large won't build fast.
Make sure you have a test kit that works with copper. Some liquid reagent test kits (API) won't work with copper in the water, it'll turn blue/green.