Firstly:
- Tell us a bit about your tank. What size is it? How old? What livestock do you currently have?
- Also, instead of telling us it is low, it is better always to include actual numbers.
- Anytime you're talking about Alk, its highly important to include numbers for Calcium (and sometimes Magnesium).
Depending on if you need to raise alk, you can buy Calcium and Alkalinity supplements. And either manually dose them, or use a doser.
However, and I could be wrong, given that you're using API and are asking this very good question, I'm guessing the tank may be relatively young. If that's so, it probably doesn't have a big demand for Calcium or Alkalinity right now. This would mean that the API maybe didn't test it accurately (which doesn't surprise me for that brand).
API is great for its affordability. Not for is accuracy or precision.
Shoot us those answers though, and we'll all be happy to help with some general guidance!