Every question opens another door to deepen the learning.
Q: Is it better to boil water till 100 degrees and cool it down till 70 if you need a low temperature?
It subjects to which mineral water you use. If the pH is high and hard, then I would suggest boiling it and then cool it down. The hardness in water will be soften after boiling.
But if you use very low Ph mineral water such as SPA or Mont Roucous which not only low with pH but also low with minerals, then I would suggest adjusting the temperature of your water cooker to the right temperature without boiling, otherwise the minerals will be further reduced if it’s boiled.
Q: Can you say the best water for green tea contains a PH of 7, Magnesium < 20 , Calcium < ??? Etc etc…. And the same for black, oolong, dark and white tea? Or is it a just a matter of your own taste ?
With water, we try to find one that can be used for different types of tea, otherwise you will end of many bottles at home.
So if we chose one which I would recommend choosing the pH in between 6,8 – 7.8. The weight of Calcium is heavier than H2O, so at end it will sink at the bottom in the pot. The dry residue between 50-500mg/liter is strongly recommended for daily use. Of course, it is again depending on the type of minerals in the water and if there are any other substances in it vs. to the physical conditions.
Sufficient Calcium is important, but too much also can cause problems. So how much intake per day? Perhaps this chart from WHO’s research can give us an idea:
The preference to flavor and taste is varied from person to person. When we learn to brew tea, we try to find the mid. Point that can be accepted and appreciated by majority.