[I don't do any water chemistry checks on my ponds, so if someone else comes along and gives you some different advice, then it will surely be better than mine!]

Fill a glass with tap water, and check the Total Alkalinity with a strip.

Stir a heaping tablespoon of baking soda into that same glass, and test with another strip.

Fill another glass with tap water to about the 3/4 mark. Pour about 10% of your baking soda in water solution from the first glass into that glass and test with another strip.

Your #1 test strip should show low or zero alkalinity. Test strip #2 should show high alkalinity. Test strip #3 should show about 10% of the alkalinity of strip #2.

Hope that helps.