This is how I made my passive intake. The intake hole is 4x12 with a box and baffle painted flat black and a piece of filter tucked in front to catch dust. Sticks out a bit inside but you could build it like example #2 to cut that in half.
Grow Room Passive Air Intake ...
- Thread starter Chester
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I do similar these days but use a 4 inch computer fan which blows through a flat Hepa filter (off a old dehumidifier) this is wired to the exhaust fan to run at the same time as per your drawing - 8 inch exhaust ( cloudline S8) - works well 1.6 x 1.8 x 2.4 h insulated rooms , in the rooms most days 2-3 times so no need for co2
Unfortunately, CO2 measuring devices are rather expensive and not of value unless you are using supplemental CO2. This is why you see the air exchange rates quoted by fan manufacturers, the flow rate is designed to keep the space at the highest CO2 level possible by maintaining a high air exchange rate.
By any chance do you know where I can get my mitts on measurements of CO2 levels in a tent being ventilated at various rates? I find it a bit puzzling how my plants would use a significant portion of the CO2 in the growdrobe in one minute, which seems to be the assumption behind ACInfinity's recommended ventilation rate. In any case, it seems to me that it is not the volume of the grow space that is the issue, it is the amount of live plant tissue being fed CO2, which may be more related to occupied floor area than total grow space volume.
I am pretty sure that I am exchanging air at much lower rates than suggested, and my plants seem happy. Perhaps they would be happier with more air, but supplying more would mean humidification that I would rather not fuss with given that I do not see a problem.
Thanks for the link.
