Chlorine Locked?

[chem geek]

12 ounces of 65% Cal-Hypo in 15,000 gallons is 3.9 ppm FC so yes that is much higher than normal, especially since it's 12-24 so 4-8 ppm FC every day. See this thread where the most typical daily chlorine usage is around 2 ppm FC and usually ranges from 1.5 to 3 ppm for most residential pools.

As for the acid and high pH, that is because of your high TA level. The TA will drop over time and the pH will become more stable. You can add more acid to lower the pH to speed up this process, but right now I think we've got to figure out the high chlorine usage. Perhaps its persistent remnants from the Baquacil conversion. I'd track your usage over the next week or so to see if it slows down. Quite frankly, if we knew in advance how bad this conversion was going to be for you, then I would have suggested changing the water instead, as painful as that might have been.

Note that your Calcium Hardness (CH) level will increase over time since for every 10 ppm FC added by Cal-Hypo it also increases CH by at least 7 ppm.