Well I am not a chemist so I don't really know what they use for the buffers, but the buffers simply help with pH swings of your
nutrient solution. I think most hydroponic
nutrients have pH buffers added. But the buffers don't adjust the pH of your nutrient solution, just help prevent swings once you have the right pH level. I always mix up the nutrient solution, then run it through the system before checking and/or adjusting my pH levels. Once it's in the right range I rarely need to adjust it again unless I have added replacement water (that was not pH adjusted first).
The right pH range is important because the plants can only absorb the nutrients in there pH range. If a pH is to high or to low then the nutrients in the solution become unavailable to the plants. Technically the plants can starve and/or show signs of deficiency, even with a perfect nutrient solution if it is not in the right pH range (therefor becoming unavailable to the plants). So the buffers are there to help prevent pH swings that can cause the nutrients from being available to your plants, but you should still regularly check your pH so you can be sure it is in the right range. Especially when needing to add replacement water, at least until you become familiar with it.