Mine were off by like .2-.3 for ALK I think with the calibration fluid. Now that I calibrate off my test kits, specifically alkalinity from the trident is always within .10 or less with my hannaThat is correct.
I will look into the ABC reagents once my supply of Neptune runs out. I have a fellow reefer near me that has been using them as well.
It just comes down to which test you trust. it will be interesting to see what my Hannah/Salifert kits say when I calibrate the Trident again against the printed values of the calibration fluid.