Here is what I use for guidelines for electrical conductivity. I use ppm, so will include that too. These are just ranges to give you an idea where to start. You need to read your plant and adjust up or down depending on plant response. A yellowish color means raise the EC slightly. Burned tips with very dark green color and clawing down means back off the EC.
Seedlings= 0.6 - 1.2 EC or 300 - 600 ppm
Veg= 1.2 - 1.6 EC or 600 - 800 ppm
Flower= 1.6 - 2.4 EC or 800 - 1200 ppm
Seedlings= 0.6 - 1.2 EC or 300 - 600 ppm
Veg= 1.2 - 1.6 EC or 600 - 800 ppm
Flower= 1.6 - 2.4 EC or 800 - 1200 ppm