This is not a "basic" understanding of pH. It was a difficult read, at best.
I'm sorry, but I've got 3 years college of organic, inorganic and bio chemisty, (one year each) I was a top student in all of those classes (my biochem was like 60 students, (Future doctors, pharmacist, chemist, nurse practitioners)
That said, there's lot's of good, useful information in here. My intentions are certainly not to bomb your thread here, but I would suggest you "clean up" your idea's and thought structure of how you try and convey information.
First, you don't even give a clear indication of what PH actually is:
The Fundaments:
measurement of hydrogen ions in solution. ie. H+ vs OH- (think protons and electons).
In
chemistry, Ph is an exponential scale used to specify how
acidic or
basic a
water-based solution is. Acidic solutions have a lower pH, while basic solutions have a higher pH ie. 6.2 is twice as acidic as 6.3...
6.0 is 100,000x times more ACIDIC THAN 6.5...
pure water is neither acidic nor basic and has a pH of 7.
At 25 °C, solutions with a pH less than 7 are acidic, and solutions with a pH greater than 7 are basic.(alkaline).
Buffer capacity is defined as the moles ie(measurement of atoms) of an acid or base necessary to change the pH of a solution by 1, divided by the pH change and the volume of buffer in liters. A buffer resist changes in pH due to the addition of an acid or base though CONSUMPTION OF THE BUFFER.
Personally, for soil grows, I check and adjust the pH of every single liter of solution added to my planters. For me, getting a good handle on this has been paramount to my success in growing the highest quality cannabis. Furthermore, I adjust that pH based upon the needs of the plant, and it's status. ESPECIALLY, if any formulas are added to the solution, the more solids suspended, ie(the more fertilizer added) the more critical pH becomes. Water without anything in it, is NEUTRAL, and doesn't require pH adjustments, because it's not got much of anything in it, it might be slightly one way or another, but that's irrelevant, because there's simply not enough solids dissolved in it, ie(molar mass) to have a "buffered" effect.
While it might not be necessary to pH adjust simple "watering' of a plant, when nothing is added to it, it's still a good practice, as a balanced pH is CRITICAL to plant metabolism and anabolism.