Ok so I have a 40 breeder set up as a QT tank. I’m running an Aqua Clear 110 power filter with the sponge and a large media bag filled with siporax bio media in it. Also running an MP 10 for circulation. Temp is 79. Salinity is 1.023. Ammonia badge reads zero. I ordered a Koran, Flame Back, and Eibli Angel from live aquaria and dropped them in. I waited a week to start dosing copper power to ensure everybody was eating good. Fish were doing great literally eating out of my hand. I ramped up the copper over three days to 2.5. For seven days everything was fine. I tested copper frequently with Hannah checker and fish continued eating well. This morning I noticed immediately fish weren’t out in front of tank swimming around as they had been. They all looked lethargic and were twitching. I tried to feed them and while they did eat it wasn’t with the same gusto I had observed previously. From my research I’m assuming this is an adverse reaction to the copper power. I tested copper levels again and it’s still reading close to 2.5 at 2.45 which is in the acceptable range from what I’ve read. My plan had been to keep them in copper power for 14 days and then transfer them to a separate breeder observation tank which was already set up and running but due to the circumstances I moved them early for the well being of the fish. Im really baffled with this as I have quarantined several angelfish with copper power in the past for 30 days without issues. Even more frustrating is I’m stuck with 3 fish who haven’t finished quarantine and can’t go into my DT. Is this just crap luck? A case of these particular fish being copper intolerant? Also if angelfish in general are this sensitive to copper then how does everyone else go about quarantining their angelfish especially the online vendors?? Anyhow any insight or thoughts on this are welcome. As you can imagine it’s been a very frustrating day for me! Thanks for reading.