What do you suggest I do? I used a different vial for the last test, but the result was the same.
Is there a different way to clean any possible residue from the vials other then just water?
I just try again or use a different ammonia kit as a 2nd opinion. It's hard to get a really accurate ammonia reader down to that level but I've gotten a bunch of false positives from api over the yrs. Nitrates are funky to.
Hanna has a ammonia checker if you're really serious about it. I'm sure it would be as accurate as you can get