Agree, we need to know the background. What is your GH, KH and pH of the source water (tap or well), and what fish? The GH/KH is related to pH so changing the pH may have to involve GH/KH depending what it now is.
To the sodium bicarbonate, this is sometimes suggested to increase pH but it is not a good method. As Dr. Stanley Weitzman wrote some years back in a series of article in TFH, it has no permanent buffering capacity, and the continual increase of sodium creates real problems for many fish, especially soft water species.
Byron.