Copper or not during quarantine?

[jackintheboxfish]

I've heard in general it's a good idea to keep a certain level of copper in the quarantine tank to preemptively treat/prevent ich. However with that level of copper it's probably stressing out the fish at least to some extent, which I feel like is actually compromising their immune system?

So except for already visible ich on the fish or the fish come from a ich infested tank, what's your preference in terms of adding copper during quaratine?

 

[overhead]

https://www.reef2reef.com/threads/current-quarantine-protocol.825055/