You are assuming that the Hanna results are better than the calibration solution. Seems like an odd way to do it. To be blunt don't chase numbers regardless of the tool you are using. It will drive you crazy. These are all hobby grade solutions be it automated or manual at the end of the day.
Manual test
Automated test
ICP tests
ICP type, vendor
People doing the tests
Calibration of equipment
See the pattern? Focus on what you can control.
@rtparty gave a sound recommendation as did
@Reefer Matt on the 2nd post. Your numbers are good after using the Neptune calibration solution. Let the Trident be the source of record since that is why you purchased it. You didn't purchase it to follow up with a battery of manual tests then compare and contrast - that would be wasteful.
You can spot check and some of us do. We'll collect a water sample from the same area the Trident draws from a few minutes before a combined test. If it isn't scheduled then we'll collect the sample then run a combined test. This way we are at the same time of day, water location, etc. Furthermore if we send off an ICP sample then add that to the mix and collect enough water for everything at that time. This way we have the water sample and time of day close enough and rule that out.
Again as already noted the Trident is going to give you data. Data you can trend over time. Add some photos and you now have beautiful data to assess and pictures to go with it. Plus a full head of hear because you are no longer pulling it out wondering which test kit or result is more accurate.
Edit:
@Reef Devils I replied everything to you - my apologies. I only meant to talk about the using Hanna results for calibration. The rest was just general reply.