Hi sorry for all the questions but I went to the lps last night and had my water tested. That's what they use(aquarium pharmaceuticals) and the guy told me one of the test was for nitrates, and it didnt come up to good. So, I bought my own test(the same) got it home and the color chart is yellow, the test in the store was blue to purple. So, now I'm thinking it wasn't the nitrates that he tested like he told me. I need to know what test is blue to purple because my water was very purple assuming he did the test right anyway since he told me the wrong test. Can anyone help was that actually a test for nitrites and he was confused? Thank you Leah