Thank's F'Rod. Here's the results using my home tap water. (I'm not at my lake today).
Plain Tap Water. 8.2 pH. 360 Total Alkalinity ppm.
After adding a heaping tablespoon of baking soda to 12 oz of tap water both of those readings were off the chart high. After mixing 10% of the soda water into 90% plain tap water both readings were still off the chart high.
Seems my home tap water is very alkaline. I'll test my lake water again next week.