First thanks for all the help. This site has been a huge help in getting my pool back under control. When I took over the pool from our maintenance guy, I couldn't understand why he kept the chlorine so high (it literally created a yellow precipitate in my 5 in 1 test kit). Once I got the chlorine down to what a normal person would consider high, I started to get algae. Then I came across this site and learned about the Cl / CYA relationship. I got the TF-100 test kit and have reduced my CYA from 120 down to 60. I live in ATL and water is expensive so I'll probably wait until the Fall to get the CYA down to 40 - 50. In the meantime, the pool looks great and my wife is in love with the feel and clarity.
So bringing the rest of the pool into balance, my typical test results are:
FC 7.5 ppm
pH 7.6 - 7.8
CH 200 ppm
CYA 60 ppm
What I've noticed is that I have to typically add acid to bring the pH down, but I usually have to add much more than pool calc says I should. For instance, I'll add enough for a .4 pH drop and only get .2. With the low TA I would have thought it would be easier to lower pH. Also with the acid add, my TA will drop into the 60 range.
I just recently added enough acid and baking soda to bring the pH down to 7.5 and the TA up to 80. Is it typical for the TA to want to trend that low? I've got a small water feature so I don't know if that is contributing to the higher pH / lower TA. We've been contemplating adding borates because of the water feature and perhaps as a fix to the low TA.
Thanks in advance!