How does Pulse measure Leaf VPD

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#1

I’m a bit confused about this product. Vapor pressure deficit is the measure of the difference in pressure between the leaf and the air. Without knowing the temperature of the leafs your figures for VPD what… assume that the leaf and the air are the same temperature?? Google “VPD calculator” and try changing the values there. A ONE degree difference between the leaf and the air changes your VPD by 0.2 or more… My canopy is often 1.5 or 2 degrees cooler then the air. Even Pulse’s page explaining VPD talks about this and the need for a infrared temperature sensor…

So, why does the Pulse system not include this? Am I missing something?

#2

I can tell by your post, you currently are not using a Pulse sensor.

I feel bad for you, you are really missing out :frowning:

Be brave, go for it, purchase one and you will enjoy first hand what the rest of us Pulse owners enjoy :smile: It really is a game changer for you and your grow !!!

After you purchase one, please come back and rant and rave about this amazing product like the rest of us Pulse owners.

Happy Growing :smile:

#3

They should add an infrared sensor and have you mount this above the canopy. That’s all I’m saying. Without it, it’s highly inaccurate. If anyone is curious I can add some numbers, or you can play with a vpd calculator online. An IR sensor only costs 15$ for a hobbyist, so much less for production quantities… It’s a pity because it’d be nice to see a product like this on the market at this price point but with decently accurate tracking.

#4

Hey Kinnik - assuming your environment is relatively consistent (you’re not changing your lighting & hvac setup frequently), you can get an accurate leaf VPD by taking into account the difference between air temp & leaf temp. We actually have a setting you set in the app to do that. You can do this once a month or so and enjoy your accurate leaf VPD.

As far as adding an IR sensor, that’s definitely something we’ve considered doing and might try to incorporate in a future product. Great idea!

#5

Thanks Peet. It’s good to know at least that is a cursory thought on the subject. So you’re telling me that I could check my leaf temp with an handheld IR meter then input the leaf difference into settings somewhere? That is a decent idea and would work for most of the time… My grow space tends to shift fairly often as I may move my light up or down to control canopy temp or adjust for growth and cycle changes. I also live in a climate that shifts dramatically from day to day (Western Canada) and as such my leaf temp difference shifts daily too with the intake. From -0.3C to -2.5C on average. Until I get some automation going it’s like a rodeo fighting the VPD bucking! I’ve mostly got it tamed now, but I do see shifts every day still that might need a little adjustment here and there.

I hope this type of tech becomes more in demand and would incentivize upgrades.

#6

That is correct, you can input it in the settings. Seems like you’re already doing that work to check your leaf temp difference. That definitely does sound like a rodeo.

Renamed the topic for clarity.

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