Advice in regards to PH

[Grinch]

Bingo. Massive TDS fluctuations cause osmotic shock in fish.

Also, taking fish from naturally soft water, and placing them in hard water, causes far less osmotic shock, than the reverse - hard to soft. The latter can cause certain death in many fish, the former (soft to hard) is generally not an issue.

+1

I've run into this issue a few times over the years through our own laziness in acclimation. All African cichlids that come into our fishroom are drip acclimated now. Many years ago I lost two newly bought SA cichlids and a pleco, fresh from the LFS going into very hard water. Unknown to me: the LFS was making RODI water to sell and was using that water along with a little bit of the local water in their fish tanks, resulting in water with a pH in the neighborhood of 7 with fairly low hardness. Their response: "You need to be making/buying RO water to keep those fish around here". SMH