Water Balance: Adjust alkalinity first, then PH . . . Or Not

[Tom.B]

We recommend washing soda and baking soda for raising TA. Borax for raising pH.

Can you expand on this a little? My TA is getting low (70) and my pH dropped from 7.4 to 7.2 (Is that a lot?) and I am confused about whether to us Sodium Bicarb or Borax. The FAQ of alkalinity isn't at all clear on what exactly does what and what range these chemical readings need to be. There are some conflicting descriptions and results when you start trying to put together a big picture. It's like, the closer I look, the less I see. :-)