Good evening everyone I have a question I noticed lately.
My AC infinity controller and my Govee Thermometer/ Hygrometer both have similar Temps and Humidity and almost identical VPD according to the temps and humidity.
When I compare what my thermometers show ( as you can see in my pics) at 80 degrees and 45% humidity both show around 2.0VPD yet every single chart I look at shows those same readings as 1.3-1.7ish VPD. According to the charts my VPD should be perfect but my gauges say otherwise.
My question is which one should I go by and why are there different suggestions for VPD? I would imagine it should be universal like a math equation X temp and X humidity= VPD but clearly that isn’t the case.
What should I go off of?
I do not have a copy or the one I usually go by on my new phone but a Google search of a few random charts showed way lower VPD
Leaf temperature offset is probably why you see a difference between your controller & a chart, or between some charts.
I stopped googling charts once I realized that different ones could be accounting for air temp, or for different leaf temperature offsets, & they don’t always state how they are calculated. I started using the Dimlux calculator & I have an infrared thermometer to plug in actual leaf temps, & the calculator gives me air VPD & leaf VPD. You can get a pyrometer at the hardware or autoparts store for maybe under $30, so it’s not a big expense.
Thanks and that makes sense. I was like I don’t get it lol that and going off VPD seems weird to me due to how much humidity they typically suggest in flower. I’m a newbie but definitely looking for everything I can dial in and do correctly and VPD is the one thing I was still struggling with.