Quote Originally Posted by kirkdbjl View Post
What does the Borax do and does it affect the PH or Alkalinity
Borax used in this manner along with muriatic acid to keep the pH balanced is a secondary pH buffer and algaestat. IMHO, it is a very useful additive and almost a necessisity with a SWCG but beneficial to any pool! It has mimimal impact on TA but really helps stabilize the pH around 7.6 to 7.7 for longer periods of time than without.
It also will deter algae for much longer than without. (I go on vacation every summer--we are talking about July in Florida--and I just shut off the pool for two week and when I come back it might be just a tad cloudy but it is NOT green. I just shock it before I leave and maintain 50 ppm borates. If I did not have the borates in the water my pool would be green in a week or less!)

There are other benefits to borates but the are subjective (water 'feels better", it sparkles more, etc.) These effects are reported over and over again and possibly have to do with how the borates affect surface tension.