I’m glad I didn’t see this post on my 1st day here…. I’d have seen the math & left.How did you get into welding back then? I can imagine you guys had/have an amazing union? This is so badass...you're awesome <3
Ok, I spent today reading up on VPD, trying to actually understand it. I think I have it? (please, anyone who uses VPD check my math and logic because what I think I figured out seems contrary to how I assume plants like their grow environment).
VPD, or Vapor Pressure Deficit, is difference between how much moisture the air can potentially hold at a specific temp and how much is actually in the air currently. This gets me close but I still need to get my IR thermometer and test the leaf VPD, which is considered more accurate.
I started out by calculating my current SVP, which means Saturation Vapor Pressure, or the maximum amount of water the air can hold before it can't hold anymore, at which point it rains or dews or some other type of precipitation. I used the equation
SVP = 610.78 x e(T / (T +238.3) x 17.2694))
T is temp in Celsius. I'm maxing out in the low 90's in the grow room so I went with 90, converted to Celsius is 32.2.
e is a mathematical constant known as Euler's Number, which I admit I was happy to see...made me feel like a college kid again. Anyways...for these purposes it's just 2.71828
Plugging all that in gave me an SVP of 4771.73.
Now I needed to use the Saturation Vapor Pressure to find out my specific Vapor Pressure Deficit based on humidity. The equation for that is:
SVP x (1 – RH/100) = VPD
RH is relative humidity. It's divided by, or over, 100 just to turn it into a usable percent. My math ended up as follows:
A.) 4771.72 x (1 - 50/100) = VPD for 50% relative humidity resulting in an answer of 2.39kPa
B.) 4771.72 x (1 – 60/100) = VPD for 60% relative humidity resulting in an answer of 1.9kPa
(A) gives me my VPD when the dehumidifier was running.
(B) gives me my VPD now that it's dead.
Now let's look at an 'ideal VPD range for cannabis' chart that I stole from the web:
As I'm understanding this...my plants should be happier now that the humidity has increased in the room? 1.9kPa is a lot closer to the green zone than my VPD before the dehumidifier went kaput, right?
I will be finding a 9v battery for my surface thermometer at which point I'll get my current leaf VPD and see where I'm at with that. Then I can either turn the lights down or up to nudge my plants into the green zone through increasing/decreasing leaf temperature? Am I understanding this correctly?
All 5 ladies are still happy. I got photos of Snowcaine 1's roots.
couple of my friends are ex-sub dudes and none of them had great experiences. No bad incidents...just...stuck in a steel tube for months and rare port calls got old quick.
