You need to get a new test kit. I also use API. I called their customer service and was told that if you don't do it correctly from the very first time you got the bottles, when you finally use it correctly the chemical that reacts to the nitrate will be way too high and give you a really high reading. You need to get a new test, and be sure to shake the 2nd bottle vigerously for at least 30 seconds, then shake the whole vial well for a minute.