At the beginning I want to say hello to everyone. After a few weeks of
lurking I finally decided to write something

The UK magazine Practical Fishkeeping ran a comparison last month, using
known concentrations of NO3.

Could you write something about the results? I actually use the Salifert
Profitest NO3 and in my opinion it's quite precise (tested in a laboratory)
and it's relatively cheap (at least in Poland).

Marcin Baranowski