Unless you are on well water, or your LFS
is on a different water source, your puffers were likely exposed to similar water parameters in your seller's tank. You might contact your LFS
to learn how they handle the ammonia. Sometimes in rural communities livestock waste and fertilizer runoff elevate ammonia levels in tap water. A small town near me has that problem.
Depending on what type of filtration you use, there are ammonia neutralizing media products that can be added to your filter basket. I wouldn't go the bottled water route either. Good luck.