What would cause the total alkalinity not to increase in pool water?

If you are using small or jumbo tabs that may contribute to the problem. You will need to add baking soda to raise the levels into the range in which your kit can detect. Use a digital meter to determine alkalinity the range. Your range should be 80-120 ppm. Or you could be adding too much acid. Get a sample of the water to a pool store soon.

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