VPD Need help

Advanced Techniques
1

Hi growers.I started to use a IR thermomether and getting the readings said my cotyledons and First true leaves are 22°C,while my air temp stays around 23-22°C and RH goes from 60-63%
Lights on.
Now,this gives me a value of around 0.9Kpa LVPD and 1.0 VPD.
The plants are 1 days old,how do I use those datas?How ti manage It?
What values to shoot for when lights go off knowing I have Botrytis spores around ?

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2

For seedlings, lower your VPD a bit. Shoot for the light green zone.

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3

Sure I ll Just let the room be cooler so It Will lower the vpd aka higher RH.
How does It work at lights out?
Don’t want to catch Bud rot again
@MrWizard

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4

I would try to increase humidity a bit, at 22C you should be around 70% rH.

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5

I saw you have inkbirds too.Those are very good gauges.

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6

Not sure on this one, I know my VPD drops about 20% at night.

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7

So you are going higher in RH right?Am I on the right track?
@MrWizard

8

Yes, I try to go by the chart, and I seldom let it drop below 23C, except at night. I use the humidity adjustment to achieve VPD target.

EXCEPT in late flower. To avoid bud rot I never let it get ABOVE 50% rH regardless of VPD.

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9

The other thing I do is use a fan to keep the air moving around after the plant starts getting bushy. Stagnant air can lead to humid pockets that encourage rot.

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10

I actually have my exhaust on off,It kicks in only when temperature goes over 23,5°C in the COOLING outlet of the Inkbird,should also work on this.The problem Is,If I extract continuosly the air never gets hot in my box, and the RH stays higher

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A small fan inside the tent, just to circulate the air inside the tent helps. I only exhaust air when conditions call for it. But keep the air inside moving all the time. Again only needed when the plant gets bushy.

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12

Spot on buddy.Thank you a lot.I have an obsession for keeping things under certain values,that Is why I got both inkbirds,temperature and Rh.
Thank you friend

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13

You’ll need a second control to trigger off of rH.

You’ll need different settings for lights out.

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14

I have two Inkbirds,temp and Rh, Isn’t It enough?

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15

For air exhaust you’ll want to hit your temp triggers and rH triggers to keep in VPD range.

You’ll need lower end triggers to add humidity or heat if your lung room isn’t within your exhaust regulated VPD efforts.

I’ve used separate exhaust rH settings for lights off (rH cutoff lower due to lower temp) to offset the lower temperatures during lights off.

I’ve used a space heater in the past, but the energy draw was not worth the cost and safety. Dehumidifier can work as well if the lung room/ weather conditions aren’t cooperating.

In a nutshell, I use AC Infinity’s Bluetooth programming for VPD control. Two separate programs for “day/night”. Lower rH cutoff so the VPD will not sink deeply in my sleep.

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16

This cannot be done with Inkbirds,I have only One trigger for a dehumidifying option for an offset value of Rh than the value I want,example 60%rh.Then I have the offset values for triggering the humidify function.Same for the temperature One.
How could I keep the VPD in range with those?
@Gizmo

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17

Add humidity :cowboy_hat_face:. Strap on a humidifier to run during lights on. Or if you want to be cheap like me, trays of water and spraying down the walls.

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