I was doubting my Hanna High Range Nitrate checker so we ran a few tests in the lab at work. Would the Hanna checker fail to properly detect a known potassium nitrate standard (20ppm)? I won't bore everyone with details at this point but I used a lab grade 1000ppm KNO3 stock solution to create a 20ppm internal standard in newly mixed salt water, zeroed my Hanna checker with the same salt water and then tested the sample containing the 20ppm KNO3 internal standard. The Hanna checker read 72.6ppm!
I also did similar tests with a few other levels of the KNO3 standard created in a 4N KCl solution which is what we normally use to analyze some of our lab samples on a continuous flow injection analyzer. In the KCl solution a 5ppm KNO3 standard reads 12.3ppm on the Hanna checker, 20ppm KNO3 standard reads 49.5ppm on the Hanna checker.
I started down this rabbit hole because my Hanna checker was telling me that my display tank sample was over 75ppm NO3-N and so we ran the same tank sample on the continuous flow injection analyzer and it gave a result of about 33ppm NO3-N granted that the method for the analyzer was set up for samples (that are not seawater) in the KCl solution but I wouldn't expect it to be wildly wrong.
I've ordered a Salifert Nitrate test to cross check the Hanna but thought I'd pose the question to see what others had to say before I reach out to Hanna to see if I have a defective unit.
Before the obvious replies come through with "take it to your LFS to check", I'll just say that there are no LFS within several hours of driving and I don't know of any local reefers or a local reefing club in my area.
I'd be interested to hear what @Randy Holmes-Farley has to say as well. Perhaps my assumptions about the checker are way off since it uses a far simpler detection method than what we use in the lab.
Thanks in advance!
I also did similar tests with a few other levels of the KNO3 standard created in a 4N KCl solution which is what we normally use to analyze some of our lab samples on a continuous flow injection analyzer. In the KCl solution a 5ppm KNO3 standard reads 12.3ppm on the Hanna checker, 20ppm KNO3 standard reads 49.5ppm on the Hanna checker.
I started down this rabbit hole because my Hanna checker was telling me that my display tank sample was over 75ppm NO3-N and so we ran the same tank sample on the continuous flow injection analyzer and it gave a result of about 33ppm NO3-N granted that the method for the analyzer was set up for samples (that are not seawater) in the KCl solution but I wouldn't expect it to be wildly wrong.
I've ordered a Salifert Nitrate test to cross check the Hanna but thought I'd pose the question to see what others had to say before I reach out to Hanna to see if I have a defective unit.
Before the obvious replies come through with "take it to your LFS to check", I'll just say that there are no LFS within several hours of driving and I don't know of any local reefers or a local reefing club in my area.
I'd be interested to hear what @Randy Holmes-Farley has to say as well. Perhaps my assumptions about the checker are way off since it uses a far simpler detection method than what we use in the lab.
Thanks in advance!