API Nitrate test kit: maybe I'm colorblind, but...

[Barliman]

Doing nitrate checks on my tanks this morning and, once again, I was struck by how hard it is to see the difference between the 10 and 20ppm colors. In the end, I was left thinking... "ehhhh, looks okay."

 

[Delapool]

I can never tell the colours either. I was using the speed which it changed colour but pretty much same of I think that maybe ok..