I don't know if anyone else checks the Journal of the Institute of Brewing from time to time, but I ran across an interesting article from earlier this year.
It discusses various ion uptake during, after and in subsequent fermentations using the same biomass.(re-pitching/racking new wort on an old yeast cake)
I figured with the ridiculous amount of is my water ruined/okay threads, some people might like to see another reason to care about it.
Here's the article: