I planned to do a water change on the QT and use carbon to removed any traces of the meds I used in there. I don't think there are parasites in the QT, but I want to make sure it's safe to put in new fish, when I get them, to quarantine before going to the main tank. I don't want to completely take down the QT because it's cycled. Since I have to buy new fish, I want to use that cycled tank to quarantine them for a couple weeks before putting them into the main tank.
I just wasn't sure about putting new, hopefully healthy fish, into a QT that's been medicated recently, so as to not make them sick. I'm guessing they would not get a fungal disease from that tank, but I wasn't sure. I've actually never has sick fish in the QT and then treated them, lost them and had to plan on using the QT for new fish. i've always just used it for the initial quarantine, so I've never really had to worry about making it safe again after housing sick fish in it.