Thanks Richard for your very interesting and educational response. Just a few comments.

1. You said "Since your bottles were inside and I assume were not exposed to sunlight". That is not correct. As I said in my post "I cut the top off of each bottle so that the water depth was about 5 inches and set them outside on my deck table. The air temperature was about 95 and there was a good 7 hours of direct sunlight, so the water in each bottle got to about 110F."

2. You said "The amount of CO2 outgassing outweighs the pH buffering effect...". Does this mean that I am better off running at lower alkalinity? If so, why do most people recommend running 100-120 alkalinity? What alkalinity would you recommend me run at?

3. You said "I found it rather surprising that your pH level returned so quickly after adding the chlorine even with the pool water sample that still measured >5 ppm." I agree and do not really understand this.

4. Is it possible that my very low CH concentration has any affect on all of this?

5. As I have allowed my alkalinity to get lower and lower, I am consistently seeing that I don't have to adjust my pH as often. I am liking running at lower alkalinity. Are there any potential problems with running at low alkalinity and if not why doesn't everyone just run at low alkalinity?

6. You said "The effect of alkalinity buffering pH so that the pH will not move as much when acid or base is added is true for a closed system." Obviously my pool is not a closed system, so I thought you were saying this does not apply. However you go on to say "So higher alkalinity (pH buffering) reduces the pH swing, but does not change actual acid/base demand." But I am not sure that I saw that in my samples as pH increased in most in samples with the most alkalinity. How can this be?

Again I really appreciate the education.

Jim