Margie,
It is not a one time and you are done kind of thing.. You have to do it over and over and over..
My TA is now pretty stable at about 50 ppm. But when I was trying to drop it, it would take me two days.. Testing and adding acid about every 3 or 4 hours, from early morning until 10 pm and then again the next day.
It changes very little at first, but as time goes on the changes seem to get bigger..
Thanks,
Jim R.