Ich is one of those multi-stage parasites that cannot simply be erradicated at the snap of a finger. You probably would have been best off QT'ing each fish for a minimum of 4-6 weeks considering you stated they were all wild-caught, and having maintained a slow introduction rate to allow your tank to bulk up it's natural bacteria colonies. Nevertheless, lesson learned I hope. For now, since you've added copper, you're going to be looking at a FO unless you do a tear-down-clean and soak/scrub every piece of equipment inside and out, and toss out the sand and rock. If you're content with a FO then you can leave the rest as-is for now. As far as the copper not "working right" or doing it's job - no, it's not that. Copper is one of those potent meds that work well on some things, but can never be considered a miracle cure-all. The reason you noticed immediate results the first go-around, is because your fish was heavily infested by adult parasites, and therefore, not only were they killed off by the copper, but you noticed the appearance of your fish improve just as quickly. But now, your fish appears re-infected as you claim. THIS is because as I mentioned earlier, Ich is a multi-stage parasite, and copper is only effective on it's "Final" stage / "Adult" stage where it's free-swimming and unprotected with a calcified casing. Ich is a rampant disease which reproduces at alarming rates, which is why erradicating it from a community tank often prooves to be a headache, and life-loss is all too common. I'm not sure why you jumped straight to copper instead of another, less destructive medication, but now that you have, you need to understand that not all meds can be safely mixed with copper based ones, and that you cannot simply run carbon and do a water change to remove it. That said, you're most likely going to have to stick to copper use for now, and run another full treatment. (You may find that you have to repeat the treatment several times before all generations of the parasite have been killed). I would suggest removing the fish from that tank and placing them in a bare QT tank, giving them a full treatment to attack those that are back on their bodies, and then leaving that display tank void and lifeless for at least 2-3 months, at which point, I'd suggest doing a full tear-down cleaning and disposing of the live sand and rock, and replacing it with new before you re-stock. This will mean a complete re-cycle, yes, but as we always try to tell people - it's much easier, cheaper, and responsible to do it the right way first, and have patience, or it could all come crumbling down on you.
