Reusing "Clean" QT water

[Keko21]

I already know the majority of the answers Im gonna get on this one but here it goes anyway- If you set up a qt tank and quarantine your fish with copper or any other medications, see no signs of illness throughout the process and eventually move the fish to your DT successfully- would it not stand to reason that the medication used killed anything negative (if there even was anything) and the tank would be ready for a new fish to QT? I suppose it's a big risk but just wanted to put it out there for theoretical discussion.

 

[Sharkbait19]

It will be ready for new fish, but I’d still recommend doing a water change and getting med levels down before getting a new batch.