Baking soda is sodium bicarbonate. This will affect KH
levels but not GH
levels. Although adding it will work temporarily, I would not recommend this as solution without KH
tests to know what the levels are now and what the desired result will be and how to maintain it. Adding some aragonite or crushed coral would be a better long term option for stabilizing KH
if this is what the OP is seeking to accomplish. In general, a stable ph within a reasonable range is healthier than trying to achieve a 'perfect' ph.