Hallo Pavel, I’m still thinking about what you wrote. How much differs the measurement of pH electrode in water with lower EC than 30? I couldn’t find nothing in the web. Just that adding NaCl would not really help. But my knowledge about chemistry isn’t very good.
And what’s about drop tests? How do they work in low EC?
And why do plants make a higher pH? My Salvinia minima grows and grows … It’s a pity that at the moment it’s to cold to send them away to blackwater aquarists who would like them….