My fish have been in copper quarantine protocol for the past 19 days at a ppm of 2.03-2.1. I moved them to quarantine due to ich outbreak in the DT. When I moved them over the only one showing symptoms was my blue hippo tang. A day after starting treatment all signs of ich were gone. On day 19 my blue hippo tang started showing signs of ich again, one of the groups has now turned brown. I’m not sure what to do? There’s no possible way of contamination from the DT I have been diligent in keeping supplies seperate. Any suggestions? I’m using copper power