From the other thread, he mentioned that he QT'd. I'm not sure what he did in QT, but he just dosed copper in the DT.
I'm pretty new to the hobby as well, but I think dosing copper in your DT was a bad idea. The rock and sand will absorb the copper and leech it back out later.
You should have pulled all the fish out of your DT and dosed them in your QT.
Please write up what you did from start to finish. Amount of time in QT, what you dosed and what you are currently dosing.
I'm pretty new to the hobby as well, but I think dosing copper in your DT was a bad idea. The rock and sand will absorb the copper and leech it back out later.
You should have pulled all the fish out of your DT and dosed them in your QT.
Please write up what you did from start to finish. Amount of time in QT, what you dosed and what you are currently dosing.

