Hi all, I'm new to this site and to pool maintenance in general. In fact, the only thing that I have going for me is that I have a background in science. Backstory of the problem... my boyfriend recently had his pool re-plastered on 5/7/20. As the builder was in his truck and nearly driving off, he said to add 2 gallons of acid to the pool after it was filled and to brush it several times a day. He said that there was no problem turning on the filter, (heater cannot be bypassed), just not to run the pool cleaner that moves along the bottom of the pool. We did as instructed, but are quickly learning that this process is a lot more complex. After doing more research, I found that an acid start up is supposed to drop the TA to zero? The TA reading taken 2 days ago was 90ppm. However, the pH reading looks to be incredibly low (very light yellow, not even associated with a number although the pool doesn't smell acidic, though it might be mildly irritating to the skin when in contact with the water) and, I am very worried that if it is truly that acidic it is going to damage his heater. However, the pool water is still incredibly cloudy from the plaster dust. Since the plaster is supposedly basic, I'm a bit surprised that the pH is so low even though I know that we added acid. At this point, my boyfriend has added about 4 gallons of diluted muriatic acid (I'm guessing between a 31% and 40% concentration), to his 21,000 gallon pool over the course of 4 days. My question is... what do we do at this point? I know that I am missing something. I feel that we are in need of some solid advice. To re-cap: The pool is still cloudy from plaster dust (we are continuing to brush it), pH levels are super off, TA is not, and I'm worried that we're going to end up damaging the other components of his pool. We are now 6 days removed from re-plastering and 4 days removed from turning on the filter. Please help. Thank you in advance.