I do not trust the API kits. I had the same problem with them saying I always had around 800ppm. I'd see my Alk up around 11 or 12 and CA at 800, my understanding is that would be impossible. You'd have to be mega dosing MG, ALK and CA like a crazy Italian to pull it off. You might find someone with a Salifert or Seachem test to compare your readings with.