Hanna Colorimeters

[Magickiwi]

Originally Posted by sphelps

mg/L = ppm for pure water only since 1L = 1kg. So your conversion will be off. Personally I would go by the Hanna and deem the other kits inaccurate.

Fair enough, adding more Rowaphos will only hurt my wallet anyway. I still plan to work out a reference solution some how. My confidence in the measurement is pretty low.