I wont even specualate what diseases, if it is diseases, w/o Vid/Pics/more info. Wondering what the pH/GH/KH of tank was right before/after wc as well as tap water?
I think it does. Usually by the next day after a change I can see that something's wrong.
BTW, antibiotics kill off nitrifying bacteria too, right? Cause I just tested my water and ammonia was now at .5. Still no nitrite or nitrate.
Also, how sensitive are fish to temperature changes? Cause when I do a 50% change the water temp drops from 78F to around 71-72. Is that too much of a drop?
Ach. Those things are worse than useless; they lower hardness but raise TDS which isn't what you want. I'd get shut on it. Besides which, it doesn't exactly sound like your water needs softening.