Hi all,The quoted reference isn't really relevant to this situation. Because there are few solutes in
@Something Fishy's water, the pH will fluctuate up and down with every small change in the acid base ratio. I use rain-water with a lower TDS in the tanks and it can easily go from pH6 to pH8 over a couple of hours after the lights have come on as the CO2:dissolved oxygen ratio changes.
It is where you have a rapid fall in pH, due to large changes in water chemistry, you get fish death etc.
You see this a lot where you have hard rock mining and an <"
over-burden containing iron pyrites">. You have a double whammy of sulphuric acid production, from the oxidisation of the pyrites, and the solubilisation of iron, aluminium and heavy metals by the low pH.
You can also get this just via increased acid rainfall and/or coniferisation of a catchment. Years ago (1983 I think) I did some work at the <"
Llyn Brianne project"> in Central Wales, when the water was extremely "clean", but the whole catchment was pretty much sterile due to acidification.
cheers Darrel