Priority: VPD or Fresh Air

My indoor grow situation is as such; I can maintain an ideal VPD with almost no inline fan use or maintain a lower VPD and increase new fresh air intake via the in-line fan. Which route is more important, perfect VPD or new fresh air?

Maybe I should find a happy medium and call it a day?

Thank you for any insight.

So welcome to the community…
How big are they so far?
If small they don’t really need as much fresh air and a good vpd can give you some explosive results sometimes with accelerated growth.

If they are good size and tent is pretty full with canopy then it may be beneficial to balance it, if in full flower i say keep that air moving and RH down and don’t worry so much about vpd…

I have 2 right at about 6 inches freshly FIM’d, the others are just rooted clones.

And thank you for the welcome, I appreciate that.

Okay, that makes a lot of sense. Thank you for the help!


Welcome to the neighborhood. :grinning:

Id say keep your good vpd then. Fan of some sort with gentle breeze on them inside and keep any flaps open for passive air flow and you be good :+1:
As they start to fill up the tent like its hard to see the floor looking down from top, or start to progress into flowering, then I’d start worrying about more air flow.
Others may have different ideas but this works good for me.


Thank you!

Perfect, I will do that. I’m in the high desert and it’s already getting quite dry here.

Thank you again.

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I keep my VPD/Temp/Humidity correct by using a AC Infinity Exhaust fan and controller and a humidifier in the tent with a Inkbird controller running the humidifier. I set the Infinity controller as the high humidity set point of control when the lights go out and temps go down. If you have a standard exhaust fan with a simple standard speed control you can use this Inkbird to control the exhaust fan and humidifier. Or a small AC, dehumidifier, heater and such. But the Inkbird will only control any to units at one time. All my settings are going to change and I will have to retune starting later today. My plants will be flipping the flower this Thursday so I will be pulling my veg lights out of the tent which are two HLG 100 V2 4000K and hanging my updated dual HLG 260 Rspec build with a HLG UVA-30. I want to start getting the plants use to the new lights and the power the flowering lights bring to the game. Good Luck!

Current controls and settings.

Plants this morning at 38 days old from helmet head sprouts.

The power of flower light that will change to plants life starting today and mandate control changes.

It’s not about which one is better. It’s about control. It’s about, lighting, nutrients, temps/rh, control and balance. Good Luck!

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