One of the contractors I am considering for pool renovation has sent me their start up procedures at my request.
I am concerned that he is not concerned about the massive use of acid during start up while circulating through my heater. The start up procedure says that when the pool is done filling to add 2 gallons of acid to every 5000 gallons of water and adjust CH to over 180ppm (will start with tap water at only 20 ppm CH). Then the pool is put on circulation 24/7. Days 3 and 4 they keep pH below 6.8 (no idea how far they might need to push it if they add acid only once a day). On day 5 they adjust pH to 7.2-7.4. On day 7 they go to 6 to 10 hours circulation time and re-install the pool cleaner.
They use sequesterant during start up and recommend using in thereafter, forever.
My heater is about 13 years old, I am not sure that it will withstand some tragically low pH. The heater manual does not give any limit on low pH, but says 7.4-7.6 is ideal but below 7.2 is marginal and 6.8 - 7.0 requires correction.
I realize that I have no understanding of what actually happens, chemically, to a pool during startup. I know that pH tends to rise, and lots of acid is needed to keep it in check, but I am stunned that these instructions do not mention any minimum pH level at all and that they have no concern about low pH going through my heater.
So, can we discuss this a bit? I am wondering if this is serious enough to delete this contractor from my list.
PS. They also say to adjust TA to below 70 ppm, which will be hard given that my tap water is 220 ppm.