Thanks, so what would you say I should do with the EC for a 26 degree room and humidty ranging from 60 - 75 ?
VPD is a range you stay within for best results. At 75% that's a bit high so I would try to keep it to 70% max.
Your EC is based upon a plan and then looking at the plant for feedback.
I wouldn't adjust EC based upon VPD. I would slightly adjust the environment to better fit your plants feedback.
If it seems to be burning slightly, running a slightly higher rh% and a slightly lower temp can help mitigate potential burn. As can lowering light intensity temporarily.
EC in a properly dialed environment is purely a read of the plants health and your experience applied. There are guides but every strain and pheno reacts differently.
So the EC advice given earlier is correct, these guys know how to read plants. The # is just a marker to use to guide your feedings. 1.2 or 1.6 or 0.7 is a means to measuring input and then reading the results and adjusting accordingly.
Plants react over several days to a week to changes, so dont expect major recovery to any stress in a few hours or just a day.