I'm looking for some advice on how best to handle the pH in my pool. The pool chemistry is really quite stable, but the catch is that I travel for work and am routinely gone for two weeks at a time. I have been in the habit of lowering the pH with MA to close to 7.0 before I leave, giving it room to drift up while I'm away. It used to drift off the scale, but since recently adding borates it seems to drift quite a bit less, up to 7.7 the last go round. It has been a workable system and the pool water and equipment are faring well, but I've recently been spending some time with the Pool Calculator (nice work on that, by the way!!) and running hypotheticals on the calculator tells me that taking my pH below about 7.4 brings me in to trouble territory on my CSI. My pool surface is Pebble Tec, which I think is similar in nature to the plaster/masonry surfaces as far as chemistry is concerned?
TF-100 water tests from yesterday:
FC 7.0 ppm
CC 0.5 ppm
Salt 3200 ppm
Borates 50 ppm
With all other parameters the same, reducing pH to 7.0 drops CSI to -0.72.
The high CH is kind of a mystery to me, my fill water is CH 180. I do have evidence of some scaling at my spa overflow and at the water line.
So I'm trying to avoid high pH to prevent excessive scaling, but now I'm learning that low pH (neutral) has risks as well. My situation doesn't allow for managing it right in the 7.4-7.8 window, so what's my best course of action?
Pool history in case any of it is relevant:
I've owned this house for right at one year. I moved to Arizona from Alaska, so had very little pool maintenance experience. I hired a local pool company to maintain it and had them start by draining, acid washing and bead blasting, and refilling the pool. So the water in the pool is just about 1 year old. At this time, the SWG was non-functional and the pool was chlorinated by a floating dispenser. I don't know exactly what product they were using. They typically made their rounds while I was out of town, and my wife reported that they were usually only there for a couple of minutes, basically just long enough to drop off the invoice. I happened to come home on the day of one of their visits, and found skimmer and pump strainer (which they were supposed to be taking care of) full of debris. I also found the chlorine float empty. I took a sample to Leslie's and they found zero chlorine in the water. I fired them immediately. With the help of the folks at Leslie's, I got my SWG back in service and got the salt levels up where they needed to be. At that point I ordered the TF-100 and started doing my own testing and maintenance. My CH was 490 at that time (this was just 5 months after filling the pool with new water) and has bounced around between 490-630 ever since.
Sorry for the super long post, but more info is better, yes? Thanks in advance for any input!