Help Assessing City Water Report/Choosing Treatment Options - Page 4

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
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#31: Post by homeburrero »

boren wrote:Would the following process achieve the above recipe

- To make potassium bicarbonate (aka RPavlis) concentrate: Mix 5 gram potassium bicarbonate into 500 ml of RO water
- To make the Epsom salt concentrate: Mix 7.5 gram of Epsom salt into 500 ml of RO water
- To make the machine-ready water: Mix 40 gram of each concentrate (80 gram in total) into a gallon (or 3.8 liter) of RO water
Yes. My calculation gives me 0.64 mmol/L of MgSO4 and 1.05 mmol/L KHCO3 in the final mix, which is a GH:KH of 64:53 mg/L as CaCO3.

boren wrote:Is this expected to be better for espresso than plain RPavlis water? How about pour-over?
I think the late Dr. Pavlis would argue that you don't need the Epsom so why add it. And he would say that for some coffees he might prefer half that amount of bicarbonate. For pour-over, which is far more susceptible to the effect of bicarbonate neutralizing the taste of desirable acidity, you are more likely to notice a taste improvement with the lower amount of bicarbonate.

Conventional wisdom was that hardness minerals in the brew water increases the extraction. Experiments with refractometers have not shown that to be true. It still is widely believed that hardness minerals in the brew water may somehow improve taste. One counterargument to that, from Dr Pavlis, is that the liquid flowing through the puck is loaded with hardness minerals, especially magnesium, that is dissolved from the coffee itself, so it seems unlikely that the relatively tiny amount in the brew water would make a difference. The nice thing about your two concentrate approach is that you can try it with and without the Epsom and decide for yourself. Both are fine with respect to scale and corrosion risk to your espresso machine.
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