Originally Posted by Sonata
When my PH went from 6.2 to 8.8 in less than 24 hours, I lost 2. It was the only chemical change. Ammonia had remained @ .5. That was not a coincidence. The drastic PH flluxuation killed them.
That's not necessarily true. Exposure to 0.5 ppm
ammonia for multiple days can kill them. The timing of their death and the pH change could've been coincidental. It's also possible that the ammonia levels heavily stressed them and the sudden pH change finished them off.
If I were you, I'd return the fish to the store, get your pH issue figured out without fish in the tank, and do a fishless cycle. I have nothing more to add to this thread. Good luck.