I can assure you that your nitrate is not zero. Try this and see if I am correct . Shake both test chemicals for at least 90 seconds. Then add bottle 1 chemicals to your test and shake for another 90 seconds, then shake bottle 2 for an additional minute and add the drops to the test sample and shake the test sample for another minute and let it set for 5 minutes, now read the the test results. Report the results and we can go from there. Ron