VPD questions

Hey all, so I’ve been working on dialing in my vpd. I’ve been trying for a few years with little success. Maintaining proper vpd requires a strong humidifier, not some cute one you buy off Amazon, but they’re cheap and what I’ve been working with. I just made a home made humidifier that has amazing output making it unbelievably easy to dial in. My questions are, should vpd be constant day and night? If so the humidity will need to be adjusted based on how much the drop in temp affects it at lights out and vice versa? That way I can keep vpd anywhere I want. Based off that, should vpd raise consistently from 1.2-1.6 throughout veg? Or I can keep my humidity the same day and night (lowering slightly through flowering) keeping the vpd within 1.2-1.6 swinging as the day night temp change? I hope someone understands this and can help!

Marthajeep010 said:

Hey all, so I’ve been working on dialing in my vpd. I’ve been trying for a few years with little success. Maintaining proper vpd requires a strong humidifier, not some cute one you buy off Amazon, but they’re cheap and what I’ve been working with. I just made a home made humidifier that has amazing output making it unbelievably easy to dial in. My questions are, should vpd be constant day and night? If so the humidity will need to be adjusted based on how much the drop in temp affects it at lights out and vice versa? That way I can keep vpd anywhere I want. Based off that, should vpd raise consistently from 1.2-1.6 throughout veg? Or I can keep my humidity the same day and night (lowering slightly through flowering) keeping the vpd within 1.2-1.6 swinging as the day night temp change? I hope someone understands this and can help!

Click to expand...

Check out the link below, they discuss VPD overnight (and much more)

ALPHA.GanjaGuy said:

Check out the link below, they discuss VPD overnight (and much more)

The Ultimate Vapor Pressure Deficit (VPD) Guide

"Why devote an entire guide to VPD?" you might ask. The answer is that the vapor pressure deficit (VPD) is extremely important for growing plants. VPD helps you identify the correct range of temperature and humidity to aim for in your grow space. With VPD you can achieve the best results while...

pulsegrow.com

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Thanks! I’ll take a look

let’s hear about the Humidifier you made

It’s just the 5gal with holes on sides, cooling material and fan on top that you can find on YouTube. I just made it much better. Instead of a desk fan I attached a 120mm computer fan with speed control to a 4” flange. Sits snug in the hole in the top, pull it out to top fill. I have a 200gph (small) pump at the bottom pushing water up to a ring attached to the pump hose with a T fitting. Supposedly pin holes in the ring for the irrigation. That wasn’t even close, so I used a very small drill bit at the right angle to soak the material without running down the inside dripping my out the holes. Then a double layer of screen between the material and interior of the bucket helps keep the water in. Had to get an opaque bucket with measuring hashes for a visible level. It’s plugged into the Inkbird, but that’s just on off. I’m looking at replacing the computer fan with an ac Infinity 4” with the controller 69, so it will control the fan speed not just on off. That would lessen the peaks and valleys. Except you can buy the 69 pro and have Wi-Fi, or buy the fan 69 and 4” fan combo, but no Wi-Fi. I need to call them. I love it, going through at least a gal a day, flowering atm, so nothing over 50%. That’s a lot of water compared to what I had prior!