I run at an average VPD of 1.1 or so. With reduced transpiration rates comes a need for higher EC. Plants need the same nutrient total for the day, but they take up less water due to low VPD, so EC must come up. Room temps are 84F at canopy, 66-70% RH, 1200ppm CO2, and 1300umol/m/sec PPFD.
I...