Hi Scott,
I just read through your entire thread, and have a couple questions. What percent was the gallon of MA that you added to lower your pH? The 75 oz which, actually I'm seeing 74 oz, BUT from what I am seeing in POOL MATH that amount is the dry acid measurement Not the liquid.
If it was 15.7% MA your pH will be fine, and should be around 7.2ppm, (the 28.3% would put you right around 6.9ppm, and if it was the 31.45% that full gallon by my calculations would have actually lowered your pH to around 6.78 ppm all of which except the 15.7% or lower% would cause you to have too low of a pH).
(I guess the most important question is: Did you recheck the pH level again at least 30 mins after the gallon of MA was added, as I see no recheck pH level listed, but if you did, what was it at that time?)
On the muratic acid to get my ph from 7.8 down to 7.2 it says add 75 oz of muratic acid. I've already added 128 oz 1 gallon so I should be fine.
It was implied in this portion of the quoted comment #15 that since you'd already added more than the amount needed to lower your pH that "It should be fine" but my concern is did you actually recheck it to ensure that it Was Fine?
My goal for asking you these questions is to try to ensure you didn't accidently lower your pH too low with that extra MA addition, as that would also not be good for your pool, nor safe/comfortable for swimming.
With your FC level now being above 10ppm a pH check at this time would not read accurately it would in fact read high because of the high FC level. So if the MA used was in fact higher than 15.7% You'll need to adjust the chemicals, possibly lower the FC level to be able to do an accurate check, add Soda ash, or Borax, per Pool Math calculations to correct this issue before moving further into the SLAM process, and especially before swimming in there.
I'm sorry for any inconvenience or confusion that this may cause, but I just want to make sure everything is correct up to this point before you continue to move forward with it possibly being incorrect. Have a wonderful day
.