Dosing phospates no results

[Randy Holmes-Farley Verified Community Expert]

Hi, I did an ICP https://aquaforestlab.com/results/S4xkGUXn90705
PO4 seems to be present also if I don't measure them with hanna 736, how do you think is it possible?

Test error is one possibility.

A second is that ICP detect forms of phosphate not detected by the Hanna, including nearly all organic forms.