@iemsparticus pH is hypothetically interesting because it's related (with temperature) to ammonia toxicity:
You can see at a high pH and temp, very very few ppm's of ammonia are tolerated. (repeating others...) When fish respire during transit, they fill the water with all manner of byproducts....from stress hormones to ammonia to CO2. Since bag temps are likely to be a little cool and pH is likely to be a little depressed, that's good for the ammonia situation. But as soon as the bag is opened and we "improve things" ammonia immediately starts getting more and more toxic.
In reality, a dead fish in the bag – or something else equally conspicuous – is usually the cause for these circumstances so it's rarely a mystery that needs close inspection. In those cases, the best course is almost always to remove the still-living fish (if any) from the bag immediately to clean water....as aged as possible, but anything will be better than
bad bag water.
This relationship of ammonia, pH and temp is still a big reason that long acclimation times are to be avoided IMO.
What
@melypr1985 says in post
#1307 is about right IMO too....I'd do no more than that in the bulk of non-emergency acclimations. Shouldn't take long at all.
