With elevated Co2, if I recall right, water use efficiency generally increases significantly. I think there is a copy of a scientific study on cannabis linked on this site somewhere that shows that. I make the uneducated assumption based on that that elevated Co2 environment all else equal would mean the plants would prefer somewhat higher EC nutrient concentration than at natural Co2 levels.
Also have always assumed (no real facts to base this on) that the best EC depends on vapor pressure deficit so what works best can really vary from one to another. Since plants drink a lot more water for the same amount of growth when the VPD is high... (hot, low humidity) a lower EC in a high VPD environment or higher EC in a low VPD environment makes sense.
Do either of these views make sense to yall? Wondering if I'm off base here. I know practically nothing about botany
Thank you both for your well thought out and articulated responses, i appreciate it. My observations of VPD are this; Either I missed the warning signs, or pretty much over night my plants were pissed and suffering from VPD. To these ends, I believe my plants pretty much stopped drinking in general.
Your theory makes sense, and my VPD certainly could have been caused by my low feed, high light/temp, low humidity situation. It would be an interesting hypothesis to test.