Bare tak with tank water and copper. You can use a hob
filter with some white filter pad to catch debris. Test the water for ammonia and everything else, ph, trates, trites. Do the water changes as necessary and make sure your copper levels are consistent. Also, my fish guy (makes house calls) said for tangs and puffers to keep the cooper at 1.00 on the API kit, but for fish with scales, you can go higher. Also, said the copper safe was better than the cupramine. Have treated many fish this way over the years with success. If you have a spare power head or airstone you can throw that in too for more oxygenation of the water.
Display tank should be fallow (without fish) for 6-8 weeks. You can leave the inverts and coral if you have in the main tank. Ich doesn't affect them, but don't dose them with copper. They will all perish!