My setup.

[David R]

"The effect of transferring hatchery-reared rainbow trout (Salmo gairdneri) from water with a pH of 7.2 to water with pH's ranging from 8.5 to 10.0 was evaluated in 48-h tests. All fish survived in the control (pH 7.2) and at pH 8.5. Survival was 88% at pH 9.0, 68% at pH 9.5, and O at pH 10.0."

Note what I highlighted. Fish from a 7.2 ph survived at a 100% rate going to 8.5 and 88% going to 9.0. Because ph is log scale, the range from 7.2 to 8.5 is huge and to 9.0 is gigantic.

I haven't read the whole article as I don't have access to it and don't intend to pay for it, but the big question is did the other factors such as hardness and TDS increase along with the pH? Unless all other factors such as temp, TDS etc etc remain constant over the experiment it is fairly presumptuous (and completely unscientific) to blame any stress or deaths on pH alone.

 

[adriaantie]

Great looking tank.

 

[Drstrangelove]

I haven't read the whole article as I don't have access to it and don't intend to pay for it, but the big question is did the other factors such as hardness and TDS increase along with the pH? Unless all other factors such as temp, TDS etc etc remain constant over the experiment it is fairly presumptuous (and completely unscientific) to blame any stress or deaths on pH alone.

Very good question. Alas, I didn't buy the article either. It would be quite shoddy science if the other factors were not controlled, however I can't validate that they were. My only point was that going from 7.2 to somewhere to 8.5 (which is quite a huge range in practice) was non lethal. Unfortunately, there aren't a lot of actual studies of the effect of suddenly moving fish from one ph level to another where the levels are extremely different.

There is a lot of evidence of shallow ponds having large daily changes in ph but none that tracked fish mortality.