My Buddy Bowl
1 Like
All of the target numbers that you are trying to hit are Leaf VPD numbers. You can’t really hit them unless you know your leaf temps & the leaf temp offset. Proper offset keeps it accurate. Know the proper offset you can pick the proper VPD chart or correct the offset setting in your controller. Then the readout or chart numbers would actually line up with your target numbers.
Even the calculators which only accept air temp & RH to give you ‘Room VPD’ still apply the air temp value input to the leaf temp value in the math (zero offset).
2 Likes
So with leaf temp. If your lights produce the best results at 12” from canopy, you wouldn’t adjust that value (or hight) in the equation right? It would be the first value added to the equation. The temp and or humidity would need to be adjusted to obtain proper vpd? Without having the leaf temp, thermometer ordered, I don’t know what the relationship is. Like higher temp raises vpd and higher humidity lowers, how does leaf temp affect the other variables? These are all questions, still learning
The air temp, leaf temp, RH, & leaf temp offset are all inter-related when it comes to VPD. you could change one or multiple values & move the end result one way or the other, or not at all. For example on a VPD chart you can find the same/similar values at different spots.
Practically speaking you would want to get the cab running to the best of your abilities, setting PPFD & DLI is helpful to put the light where you need it to be, & then start tracking leaf temps in addition to the other values, calculate the leaf temp offset, & then pick the appropriate chart (charts are generated using one leaf temp offset each) or just start using the leaf vpd calculator, & you can make adjustments with air temp &/or RH from there, & keep tracking.
In your case right now, if you check your readout, post up your current air temp, RH, & VPD numbers, & we can at least figure out what offset your device is calculating with. (Probably zero offset, but why not check?)
Makes sense, will do