freedom 35

So, according to the Co2 enrichment guide...

"Standard growing conditions typically include concentrations of CO2 at 300-500 ppm, temperatures between 65-80°F, and relatively low humidity (20-40% rH). Studies have shown optimal growth and yields at 90-95°F, 1,500 ppm CO2, 45-50% relative humidity, 7,500-10,000 lumens/square foot of light, and vigorous air movement both above and below the canopy. CO2 enrichment under 80°F, under 7500 lumens/sf, or above 50% humidity is not recommended because plants will not be conducting photosynthesis quickly enough to benefit from the enrichment."

Can anyone else who uses Co2 tell me what temperatures and humidity you shoot for?

I feel like 90-95 temp and 45-50 humidity is kinda high. Maybe its just because im so used to active air ventilation. Im just looking for some input here.....thanks!

__________________
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LJB

90-95 degrees optimum? I'd like to know what studies the authors of that guide are referring too.

In general, we should aim for 75 - 85 degrees on the leaf surface of the canopy and 50-60% relative humidity.

You might want to read this study. I think it's the Gold Standard of research for us right now.

Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions

Suman Chandra1 , Hemant Lata1, Ikhlas A. Khan1, 2 and Mahmoud A. Elsohly1, 3

(1) National Center for Natural Product Research, School of Pharmacy, University of Mississippi, Oxford, MS-38677, USA
(2) Department of Pharmacognosy, University of Mississippi, MS-38677 Oxford, USA
(3) Department of Pharmaceutics, School of Pharmacy, University of Mississippi, University, Oxford, MS 38677, USA
Published online: 26 February 2009

That was conducted with RH at 55% +/- 5% at all times.

30c and 55% RH = 2.31 Vapor Pressure Deficit

Interestingly enough, I've read elsewhere that tomatoes do best with a temp of 28c and a 2.25 VPD, which is not far off.

Here's a nice little paper on VPD from a couple researchers at Ohio State: Greenhouse Condensation Control: Understanding and Using Vapor Pressure Deficit.