doublehelix wrote:There's ~100 mg of potassium in a cup of brewed coffee, which is far less than what a banana offers: ~0.5 g (500 mg). Haven't done the arithmetic, but this all far less than what Pavlis water offers per cup of coffee.

If I correctly remember-- Pavlis liked adding a bit of potassium bicarbonate to lift the water pH in order to discourage copper corrosion. He substantiated this view with his chemist's knowledge of copper corrosion mechanisms.

Brewed coffee has ~ 8 mg of Mg per cup.......

doublehelix wrote:There's ~100 mg of potassium in a cup of brewed coffee, which is far less than what a banana offers: ~0.5 g (500 mg). Haven't done the arithmetic, but this all far less than what Pavlis water offers per cup of coffee.

Spot on. The rpavlis water at full strength (100 mg/L potassium bicarb) works out to 2-3 mg of added (from the water) potassium in a doppio. To effect blood potassium via what you eat and drink, you'd need to overdo potassium supplements. (As Marcelnl says, other things can cause a spike in blood potassium - https://www.mayoclinic.org/symptoms/hyp ... m-20050776 )

RyanJE wrote:In theory it should be easy to test. One could make the bicarbonate 100ppm water and compare to Say 40ppm alkalinity and 80ppm magnesium hardness which is closer to SCA spec.

Not to quibble, but I think it's worth pointing out that rpavlis' recipe at 50-100 mg/L potassium bicarb is only 25-50 mg/L alkalinity (in CaCO3 equivalents.) He's already on the low end of SCA recommended zones for alkalinity.

homeburrero wrote:

Not to quibble, but I think it's worth pointing out that rpavlis' recipe at 50-100 mg/L potassium bicarb is only 25-50 mg/L alkalinity (in CaCO3 equivalents.) He's already on the low end of SCA recommended zones for alkalinity.

Yes. I was referring to testing the difference with magnesium added. Meaning, would having the additional 80ppm hardness from magnesium Affect taste.

And according to Mitch/CwM in a previous post, it should make quite a difference to someone like me who roasts light and likes it bright. As opposed to Robert's formula which i have been using. OTOH, Robert's math where the amount of magnesium in the water is dwarfed by the amount in the coffee is pretty compelling. So we will see.

-Peter