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.