I stumbled across this thread while trying to research why my Hanna Marine Master is reading is so much lower than either the API or Red Sea test kits.
Here's the background - I've only been at this for about 7 months and, in that time, I jumped from API to Red Sea test kits due to concerns about accuracy, but those seem to be a bit unfounded as the readings seemed to be relatively close in most cases. I recently decided that I'm going to drive myself nuts trying to determine which shade of yellow/orange/blue a particular test result yields, so I decided to go digital and picked up the Marine Master when it went on sale recently.
Testing Nitrate with the API/Red Sea had been resulting in readings in the 40-50ppm range, so imagine my surprise when my first reading with the Hanna was 1.3ppm! While potentially delighted, I was obviously skeptical.
I retested this morning with the Hanna and the Nitrates came in at 6.5ppm, which still seemed low, so I tested with the API (I'm out of one of the Red Sea reagents, so no verification there). The result from the API test was in that 40ish range, so I decided to do some research and came across this article
API Nitrate Reagents 'Usable' with Hanna Checker which laid out the steps to use said reagents, so I did. This time the Hanna reading was 11.3ppm, even though the color was actually the same as the straight API test (which tells me the samples were equivalent).
So, Now I'm completely confused. I like the idea of testing both against clean salt, which I will do tomorrow as part of my water change, and I realize the article mentioned the Hanna Checkers and not the Marine Master, but I have to think that it would work on both platforms. I guess I'm just looking for any input/advice/thoughts on the subject.
