[JDT1234]

Originally Posted by ca1ore

Did not read the linked threads, but I think it HIGHLY unlikely that things like CA, MG and Alk would have anything to do with your fish losses. While it is possible that something like copper is the problem, I doubt that too as most places that sell fish run low levels themselves. I think it is much more likely that there may be some kind of underlying disease problem in your tank. The resident fish have become immune to it; the newcomers not. I will say that I have been having all sorts of problems lately with bacterial infections in fish to the point that I now treat all proactively in QT with fish flox. I would also suggest that you slow down, let your tank sit as is for a bit before attempting to add anything new. The cardinal rule of reefing is that nothing good happens fast.