I am helping a friend with a fiberglass pool and was looking for a better understanding of how little pools balance their chemicals. We ran tests and found our results did not agree with a pool store my friend had been using. I came across this site and decided to join. After reading a number of sticky's and posts, I realize I am writing heresy here, but I would like to clear up a few things on borates in the pool.
When you dissolve borax in water, you get a weak lewis acid, boric acid and a base tetrahydroxy borate. The pH buffering ability of borax doesn't start until an upper pH of 8. The pKa of the boric acid is over 9 and this will be the area of highest buffering capacity. Borates and borax have virtually no buffering capacity in the pH range of 7-8 in a pool. Borates are weak alkaline products with weak alkaline chemistry. The silky feel is a type of saponification of oils from the body and not anything to do with a water characteristic. Saponification in its majestic form is mixing lye with animal fat to make soap. Hence the silky feel.
The primary buffering capacity in pools is due to alkalinity. Specifically due to the bicarbonate buffering system. Once you go above pH 6.3 you have a carbonate-bicarbonate buffer until around a pH 8.3. This is why alkalinity is one of the most important chemical parameters to maintain in a pool. Alkalinity in our pools is mostly carbonate. The other half of the chemical species is not important and is just a counter ion. Carbon dioxide from the atmosphere and the carbonate part of alkalinity form a buffer system. This is a lesson one learns in Indiana since the ground water is typically 250-450ppm alkalinity. Proper maintenance of your alkalinity is the most important aspect of pool chemistry maintenance. You will fight an uphill battle until you get your alkalinity within acceptable ranges for your pool. You will waste time and money until you bring your alkalinity in line and keep it in line.