Thanks for the additional info. I have a few comments / questions.

1. I just purchased enough bleach (found it on sale) to last me the rest of this season. I normally close early to mid September. And the only local pool store I have had never heard of using bleach let alone selling it. When I asked from Sodium Hypochlorite, they looked at me like I was an alien. When I told them it was bleach, they still looked confused. So I can't find the higher strength stuff, but I have used at least 3 different brand names of bleach this year and seem to get similar results.

2. I forgot to mention this in my past post, but my CA is in fact 10ppm. I have very, very soft water. Using my Taylor test kit, it only takes one drop to get a color change. I have asked if this is a problem on this board before and even Ben has said for vinyl pools low CA is not a concern. I thought about using some Calcium Hypochlorite for a while to increase it, but I can get bleach cheaper so I have just stuck with bleach.

3. I have not really noticed needing to add acid any less frequent at 120 TA than at 80. However I have not really been keeping records either. So it may be but I just have not taken notice. I still add acid about once a week.

4. Now for a radical question. If having high TA causes an imbalance in the water and if having low TA causes the pH to want to increase less, why not just go with little or no TA? I understand that pH would swing more, but from what I hear you saying it will tend to reach equilibrium and maybe the pH would increase 0.1 units per week. That would not be so bad. So why would I not just have very little or no TA so my pool would be at equilibrium?

Thanks again for the interesting posts.

Jim