Originally Posted by MrBungle
Good light 1 kw DE... no co2 enrichment... temps are in the low 80s with the lights on RH is 48-52% ... dark time low 70s and haven't looked at dark RH... I don't know which VPD chart to look at and trust...
Have you also attempted to calculate VPD on your own? It's been some trouble for me. I can't find an equation
to trust. There are a few variations out there all with different coefficients. And no explanation for why they use these coefficients. As far as the charts, most seem to have the same numbers, but some are more relaxed as to what is best for plants overall. I think .8- 1.1 is where we want to be depending on your situation.
Like this one appears in a dopey grow video but also appears in a textbook or two, just no explanation for using these coeffeicients vs. Sonnheim coefficients or any other standards:
VPSat - VPAir = VPD
VPSAT= 610.7 x 10 ^((17.5 x Leaf Temp.)/(237.3 + Leaf Temp))
divided by 1000
VPAIR = [610.7 x 10 ^((17.5 x Air Temp.)/(237.3 + Air Temp.))
divided by 1000] x (Rel. Hum./100)]
Does no one truly know or agree on critical temp points or true boiling points? Why 237 when some use 270 or 243?