I tested again and it came in at 43. I stopped dosing Nitrates altogether. I'm going to proceed on the premise that Hanna is right until I see evidence otherwise. I'm going to take it slow and let the nutrients come down gradually. Hopefully, with my daily water changes and a good skimmer, I should have no problem bringing that number back down. I'm also hoping that I will see a decline in the algae. I don't know for sure but I think those new urchins are eating the algae I've been worrying about. I'm thinking about ordering 5 more.Whoa that is pretty racy. I really like my Hanna HR. I was using NYOS and Salifert before. My Hanna tested lower than those other tests. No experience with Red Sea kit.