@Rob1 Thanks for your insights. I was doing my tests by filling the reservoir & did each test in a block; running through two tanks worth of each mix that amounted to about 5l, which thought would give sufficient exchange within the brew boiler for a realistic set of results. This took about a week per test at 3 espresso’s a day with 3 different beans (Light Espresso, Medium Omni & Sugar Cane Decaf)
I started noticing a gradual change after the 2nd/3rd day with a marked difference by the end of each test. I didn’t however do a control, which is probably something else to try.
I have to admit that I’ve always associated the erratic/patchy/wispy flow from the PF to be associated with channelling, which has been a source of (possibly misguided) frustration & although there hasn’t been any noticeable holes in the puck, I was thinking there might be something going on under the surface.
It’s only relatively recently that I got a Zero Jug & started experimenting with different mineral make-ups. Prior to that I was using Brita filtered tap water. The tap water was already pretty soft but I wanted to remove the chlorine taste. The side effect was that when I measured the pH of the unfiltered/filtered water it had dropped from 7.3 to 5.6 & even though the boilers are SS there’s plenty of copper & brass bits so was concerned that it might not be doing my machine any favours.
Your explanation regarding the CO2 production & crema possibly giving the perception of better extraction at the higher ratios is something I’d never even considered & is certainly something worth exploring further.
When I was using the Brita water, there was a noticeable acidity bias, which although I generally like; sometimes it got a bit too funky. Like yourself I did think that there would be more noticeable differences between the mixes used in my tests & it may just be my palette. I was thinking that although the mineral content of my mixes was changing; the ratio of the minerals remained the same at 2:1 & that might be why I wasn’t finding much of a difference.. Something else to try might be altering the ratios & see what impact that has.
Sooo many more tests to do, though it does take a bit of time for each test so it’s going to be an interesting journey
