Does anyone know the shelf life on test kits? I did a test yesterday with an API and it turned blue as soon as I added the second reagent. I measured about a 2.0. I checked again tonight and the same result. I pulled out my Hanna checker and received a 0.00. I’d love to go with the Hanna over the API that is a few years old. But, it sparked the question and I can’t find an answer through Google.