I discovered TFP about six months ago when in the process of draining the pool and having 12 years of Calcium buildup blasted off the tile. I've been using the TFP method ever since to great effect....thank you TFP !!!
The TFP recommended pH is 7.5-7.8 and every week when I do my tests I find pH has risen to 7.8, so I add enough MA, from PoolMath, to take it back to 7.5. I added 25 lbs of boric acid in April to bring my borates level to 25ppm and when that didn't stop the pH increase I added another 25 lbs in June, but again every week ph had risen to 7.8. TA has been rock steady at 70 all this time.
A couple of weeks ago I looked at my log and realised that with no borates I had been adding 14 ozs of acid per week, with 25ppm borates I had been adding 29 ozs per week, and now at 50ppm I'm adding 43 ozs per week. So all the borates had done for me was increase acid use by 30 ozs per week. !!!
After thinking about it I figured that didn't make any sense, so I didn't add any acid last week...this week I tested again and my pH was still at 7.8. It looks like the borates buffering effect in my pool occurs at pH 7.8. So my inclination is to continue not adding acid and see how long I can go at 7.8. My worry is that I've read plenty of threads were people have pH lower than 7.5 but I've never seen anyone with ph higher than 7.8.
So if my ph goes up to 8.0 or 8.2 is that a big problem?
PS. At 73°F water temp and pH of 7.8 my CSI calculates out to -0.35, and at ph 8.2 it would be -0.27, so that looks pretty good.