I always had such a hard time measuring the concentration of cupramine. Sounds like you have to deal with it. Good luck.Maybe is because you are using “cheated” copper [emoji23]. Couldn’t resist.
But not really, all three cases happened at very different points in time on different QT tanks and typically fish were doing well until the first drop of Cupramine hits the water.
Unfortunately it is impossible to get Copeprsafe or Copper power over here. The only thing I can get is Cupramine which I believe is the main reason for my difficulties....