@GrnyGrows …your fresh air looks like in your case will happen when you open your barn door to come in or open windows…just you guys going in and out of the barn would bring in enough CO2 for the plants and the time you spend in there with them will add CO2 …don’t get caught up with CO2 levels on your first grow … the normal amount in the air and you exhaling will be sufficient and not be toxic.
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OM gosh, thanks for talking me down off the CO2 cliff. Bam!
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I would pull air from outside at night if its hot during the day and run lights at night also if you don’t have problems with light leak during daylight
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I run lights at night too. It balances out the hot/cold. Daytime lights send my temps too high and night time dark is too cold. By running lights at night, I am cooler in the day, warmer at night. Bring fresh air in from the bottom (that is more than enough CO2) unless your temps are high (>82F).
I have air circulation 100% of the time (setup made by using pc fans (4 of them, on pvc cage that also serves as cage for SCROG) and I mount them to the horizontals that I can turn for directional purposes
This is separate from my intake / exhaust system. I exhaust from the top, slight negative pressure, using a fan speed controller to get it just right. This way * can* adjust VPD with th touch of a dial
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That’s what I’d do. My dark period is timed during hottest part of day. 
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If it is at all possible it’s best to pull night air in your grow but i know alot of grower’s don’t have the that option.
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I really don’t. Have to use heat and AC for control.
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Plants give off CO2 at night and O2 during the day so nightime air has a higher concentrate of co2, that is why we pull in night time air
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is it a measurable difference?
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yes it is. Plants take in co2in the day and produce O2. At night, its reverse. They TAKE IN o2 AND PRODUCE CO2
Night air contains much more co2 than day air. If you can bring in fresh air at night, it is like having co2 bags in your tent BUT…It does NOT stay there in the daytime if you continue to bring in fresh air. CO2 is heavier but most of us intake from the bottom and exhaust from the top
All in all, not measurable difference at the finality
During photosynthesis, that is when we want the higher co2 levels and that coincides with higher temps (>82F) for it to be worthwhile unless you are a commercial environment
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Crrydinffe 2000w or yintatech 2000w ? Witch is better ? Anyone got a opinion? Almost same in size and actual watts trying to deside for 2x4x5 tent. Or suggestions and recommendations pls Also growing autos
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How about a grow science 300? Anyone opinions thoughts
Upgraded to maxisun pb2000pro. Hopefully get better results. Was using 2 dmvo 1000w burples.
If u can run ur lights 24/7 autos need it
Old thread but 24/0 is arguable. 20/4 as imo a need a rest and b the extra use of energy isn’t worth the extra bud17% less energy for nowhere near 17%yield boost
My experience with autos 20/4, will work just takes longer to Finnish up .what’s couple weeks not.much longer to wait
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