> The EC moving from 1415 1.41EC to aorund 1360 1.36EC is not that crazy. only a difference of 55 or 0.05EC, hardly anything.
You should use Siemens, the EC unit of measurement, if you don't want it to be too confusing: 1415μS (1.415mS), 1360μS (1.36mS), 55 μS (0.05mS). ^^
> Noice, how do you measure your pH and EC like that?
Probes connected to a logger (there are few commercially available, but you can do this with a Raspberry Pi or an Arduino) and kept into the tank permanently.