I've learned how to lower TA by adding acid, then aerating to bring the pH back up. I understand that with normal use the pH will rise naturally so I've needed to add a little muriatic acid almost daily keeping pH close to 7.5 (or slightly below at times). I recently finished using Dichlor daily to reach a calculated CYA of 30ppm, and have switched to 8.5% bleach and have about 50ppm Borates. Initially I brought the TA down from 220 to 60, it fell to 50, but now it's at 40, so I believe I need to add some more baking soda. My question is; should I expect the TA to keep dropping over time due to the ongoing need to add acid? Or does a falling TA (albeit slowly) imply that I'm perhaps adding more acid than I should (I occasionally have overshot a bit, down to pH 7.2)? Or was it a Dichlor effect and should now become stable?
My initial TA target was 70ppm, but when it fell to 50ppm I was told here that 50's fine. Now at 40ppm I arbitrarily set the poolmath TA goal to 60, to calculate the baking soda need. Would a higher goal TA (say 70) decrease the need to add acid daily by better buffering? Or should I just expect to check and replenish the TA every so often and aim for TA of 50?