...every day you add chlorine to your pool your pH goes up 0.15 and the chlorine then gets used up during the day and your pH drops back down resulting in a net increase of 0.04 per day. This is at a TA of 120.
Then something is definetly adding more to pH than the bleach. In 5 years, I have never seen this small of a net increase in pH. I have only used generic brand bleach (5.25 and 6%), but have used a number of different sources. All seem to have similar results. So I don't understand what it could be. I only add bleach and muriatic acid, then maybe adjust alkalinity once around mid-summer with baking soda.

Thanks again for the info.

Jim