PO4 test kits - Hanna VS Salifert

[GoFish]

Just picked up a new Hanna ULR Phosphorus kit and tested tank. It says 72, so after some math (72 x 3.066 / 1000 = 0.221)
Then tested with Salifert kit and as always it shows only a slight hint of blue. Somewhere in the range of 0.00 - 0.03.
But based on what the Hanna ULR shows the Salifert kit should be showing a really blue test result.

Using only Salifert for the last couple years I've always had consistent test results.

Just did some major water changes to a new salt brand over the last week and tested last night with Hanna only and its down to .23 ppb (0.07 ppm). Haven't cross checked this with Salifert yet but assuming that will still show low

What should I trust more, Hanna or Salifert?