Today my Sttoke swirl cups arrived, so I'm doing a little Water-comparison between the 117ppm water I made (somehow the Prodigal I brewed did taste too bland but sour, but maybe it's just my pour over skill issues) and my 73ppm filtered tap water.
I pre-heated both waters and filled them into servers while I grind 11g coffee for each cup at 4.0 on zp6, then I heated them up again to 98°C, poured them from my kettle back into the glass server and onto the grounds in the cups, so the extraction started just a few seconds apart.
Interesting, after 7 minutes the crust on the 117ppm water sinked down while the crust on the 73ppm water is still intact.
The lower ppm water also had more foam on top.
Both cups are still at 73°C after 10 minutes.
Those cups are double wall thermos cups with an emaille coating, so they're staying longer hot compared to normal ceramic cups. The difference isn't that big actually, the 117ppm cup tastes a little bit more juicy, probably because of the higher GH while the 73ppm cup feels more creamy, but both have a nice acidity.
Actually I'm getting the notes more intensive on the aftertaste, which comes delayed by a few seconds and lingers for a bit. it's hard to tell which water I like more. The only thing I can say is some coffees works better with a higher GH and/or KH than other coffees. If it's too acidic or sour I'd either reduce the GH or KH, or both, but I think both have an impact on how we perceive the acidity and the mouthfeel.
My sensory skills are noob level tho. I can't even describe what I smell from the brewed coffee, and I also don't smell a difference.