On 10 May 2010, due to high CYA (~150) and CH (~550), I drained our pool of approximately 80%-90% of the water and began to rebalance. Unfortunately, I've been unable to keep the pH balanced and have had to continuously add acid. Here's a recap, summarized from our chemical log.
11 May - pH=7.8, TA=170, FAS FC=1, FAS CC=0, CYA=0 (or less than 20, anyway), CH=240.
I added Bleach and Baking Soda to balance and won't comment further on them except as necessary.
16 May - pH=7.6, TA=110, DPD FC>2,
By this time I have added 166 oz. of Muriatic Acid and believed I was nearing balance. This was not to be.
29 May - pH= 8, TA=90
By this time I have added an additional 62 oz. of Muriatic Acid. Since I use Trichlor pucks when gone for a few days, I decided to bring the TA up to about 100. I used 1 pound Dichlor to bring up CYA.
17 June - pH=8, DPD FC~3
By this time I have added an additional 125 oz. of Muriatic Acid. Also, I've become tired of breathing MA fumes and have bought Dry Acid.
24 June - pH=8, DPD FC>2, CYA =30
I've added an additional 63 oz. of Dry Acid in the past week. I've also noted an increase of pH immediately after the addition of liquid bleach, which I first attributed to the local H.E.B brand, but it appears present even with regular Chlorox. I have now shifted to Trichlor tabs exclusively, which seems to slow the need for Acid, adds CYA, and is simpler, given my constant need to add acid.
2 July - pH=8
Have added an additional 63 oz. of Dry Acid. Have noted that rainwater and tap water have pH=7.4.
9 July - ph=8, TA=110
Have added an additional 38 oz. of Dry Acid.
17 July - pH=7.9, TA-130, CYA=34, FAS FC=3.5, FAS CC=0
Have added an additional 40 oz. of Dry Acid.
Edited after questions: Also, to level the TA, since 29 May I have added 27 pounds of Baking Soda.
So there you have it - over the time period, I've used 9.8 oz. of Muriatic Acid per day , then changed to Dry Acid and am using 7.0 oz per day.
Do I have a problem?