Ok...so....here is an update:
I dosed 2 capfuls of neophos about an hour or so before the NP did it's reading today. It should raise the Phos by about 0.02 based on the formula on the bottle.
Yesterday the NP measured 0.04...today it measured 0.05.
Yesterday the Hanna got 0.02...today it measured 0.07.
Technically I guess both sets of numbers are within the Hanna ULR tolerance of 0.02. Also..."technically" if I dosed enough NeoPHos to raise my tank 0.02 but the NP only registered 0.01 increase ...that's still probably within the tolerance range for the NP
I dosed 1/8th tsp of Sodium Nitrate which should have raised my Nitrate by about 1.4
Yesterday the NP measured 4.4...today it measured 5.6
Yesterday the Hanna got 3.7..today it measured 4.8
Overall I feel pretty confident in the Nitrate measurements. I don't feel that way about the Phosphate numbers but with the numbers being so small and the tolerances being what they are...it's probably "accurate".
I was worried my NP Phosphate numbers were heading down to 0.0 like others have posted...but it did see to move back up with my dose today.
Unrelated - you wrench on the Eagle?