I took some advice about the different test kits. I took my water 2 a couple of Lfs and watch them do a test. Both said that your water is perfect. They do not shake the bottle or the test tubes for nitrate after they cap them. The instructions clearly state to shake the nitrate tube for at least one minute. That's what I've been doing. I took my test kit which expires in 2017 and did a test, shaking the bottles a bit, and the nitrate tube for one full minute after dropping, and the another tube with no shaking. Welcome to find out the tube with no shaking looks awesome, but when you shake the nitrate tube for 1 minute after put the cap on it it shows almost 80 parts per million difference. Has anyone else had this issue?