@Colin_S it seems the lower the No3 the more the hanna has been off from the IOND. In the upper values like this image shows it within 1-2 percent but notice when testing the lower vaule tanks where it between 5-10 and 0-5 and used both the high and low nitrate tester it would be between 5-7 percent off.
The ION across the multiple submission of water test was always within 1-2 percent across all the readings.
Back to Back also is where I saw the most deviation on Hanna, and again it the human element of making sure you drew the exact water (I used a scale) made sure all the regents were in and so forth.
I am slowly using the IOND to lower the nitrate on this tank which was over 50 when it started back in a January

I am aiming for 10, and this tank has never had any water changes.