In my reading here I understand some pools just use a lot of acid and at 19 months old my plaster may not be fully cured and adding to the problem. However I only used about half as much acid last year and the SWG was just added in May so I am thinking it is the major culprit to my high acid demand. One thing I have no clue as to why it is happening, my TA drifts up with the pH. I started this spread sheet posted by another TFP member when I got my TF100 Kit. (I was previously using a Taylor K-2005.) Blanks mean test not taken. We have had a little rain around the 12th. Any suggestions on how I can lower the acid demand? How low can I take TA safely? 30-40? Why is TA drifting?