jmm007 wrote:Can someone please post a link to the rpalvis water recipe?
Dr. Pavlis discussed it in various places, inluding this post: 1977 La Pavoni Europiccola with green deposits/scale
rpavlis, in linked post above wrote: .... I personally use, as I have stated many times, about 0.5 to 1.0 mMolar potassium bicarbonate. You can simply add from 250 to 500 milligrams of potassium bicarbonate to a 5 litre container. You can use sodium bicarbonate too, but I do not like doing that because it seems to create peculiar flavours because Na is very low in coffee beans.
(The container was filled to 5 liters with distilled water.)
You'll find other recipes geared towards 1 gallon or 5 gallon jugs, and recipes that make use of strong concentrate solutions so that you don't have to weigh out tiny amounts.
Here's one easy example:
Get a 750 ml stoppered bottle, add 9.6 gram of potassium bicarbonate to that, and fill with 750 ml of purified or distilled water. Shake well and keep in the fridge. Then for every US gallon of purified water just add 1 to 2 tablespoons of that concentrate. (1 tablespoon works out to 0.5 mMolar bicarbonate -- or a total alkalinity bump of 25 mg/L as CaCO3.) If you go with sodium bicarbonate (baking soda) you would use a little less - about 8.1 g instead of 9.6 g in that concentrate bottle.