No, buffer will increase the pH or least temporarily spike it. The pH of the water is relative to the time of day tested and possible organics/CO2
working against it or O2
working with it. If your pH is high early in the day, a water change will normally fix any chemistry imbalances. If the pH is higher later in the evening, it's not normally something to be concerned about. Algaes in the system are producing O2
and aiding the rise in pH. Conversley, at night (no light) the same algaes are producing CO2
working against the pH so there is a natural rise/fall throughout the day and night. What your looking for is an average. Best tested at some point midway through the tanks photoperiod. You can do a series of tests (morning/midday/evening) to see what I mean.
The best use for the buffer you have is for low alkalinity, not pH problems. If alkalinity (balanced with Ca
) is in the right range, pH issues will most commonly be environmental in nature, not chemical.