I did not test for CYA, assuming it is low to medium. I did have to add water this year, and the only CYA that gets in there is from the pucks that I usually use.
After first shocking the pool to make it swimmable, I decided to go after the stains after joining the forum.
I let the chlorine gradually fade away to zero, with the TA and pH in the good range.
I bought 10 pounds of bulk food-grade citric acid and put six pounds around the 30,000 gallon pool. Most of the stains disappeared, but not all. This is the first time I have gone after the stains in 4 years. So I added the rest- 10 pounds of citric acid in total.
My plan is to wait 24 hours, then put in 32 ounces of hth metal remover and let that perk for a few hours.
Now comes the question:
The pool was getting a little cloudy due to the lack of chlorine when I started. After the sequestering agent has had a few hours to do the job, would it be time to shock it with chlorine again? The pH should be ridiculously low and this shoulw maximize the chlorine doing its job.
Then, I have bulk baking soda ready to go to put in as much as I need to get the pH to 7.4 or so.
Thanks in advance.