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.
http://www.advancedaquarist.com/issues/may2002/chem.htm
Cheers
Steve