According to the pool calculator, a 30,000 gal pool with zero alkalinity would require 35 pounds of baking soda. That's a lot of baking soda! I don't believe your water has zero TA (total alkalinity).

To go from 2900 ppm salt to 3200 ppm salt you'd need to add 75 pounds. I know nothing about SWCGs but 3200 ppm sticks in my mind as a target. Your owner's manual would tell you.

Is there another pool store in your vicinity where you could have the water tested?