johanpaul ha scritto: Well, when I took the first test for nitrite I also took a test for nitrate. I had the both test bottles in the same hand shaking them violently to have them mixed well. This is what the instructions for the JBL nitrate test says I should do – but the nitrite test does not say I should do this. Apparently if you shake the test bottle of JBL nitrite test too much, you will get a false positive reading as a result. I never thought that shaking the test bottle would cause any harm – I mean it was not explicitly forbidden or anything. But apparently you shouldn’t do that. Only gently see that the two different liquids you dropped into the water are mixed and leave it alone for three minutes.