[queequeg152]

Originally Posted by PerfectGrower

(CO2 settles)

no it does not.

[queequeg152]

Originally Posted by Reckless

CO2 in a greenhouse is a terrible idea. A greenhouse needs to be ventilated otherwise it gets too humid and too hot. So you're gonna blow air into it and monitorzing CO2 levels at the same time.

Man be glad you can use the sun not a HPS aznd forget about the CO2

ive seen it done once. it was in a horticulture journal documenting the cost benifit of co2 for the production of some sort of very specific very fancy ( probably very profitable) flower. they were growing transplants during the winter through spring.

this was in holland though. quite a bit colder than most of the united states.

they were using supplemental lighting for the evenings and using biomass (wood pellets probably) and natural gas if i remember correctly. they were not anywhere near the co2 figures indoor growers like to keep though... i dont think it was even double the normal co2 levels.

[queequeg152]

also to clarify... by "seen it once", im talking about seeing it randomly when reading about other greenhouse related shit.
its not something ive ever investiaged... id be suprised if there was not a great deal of information on it. i mean... considering the huge volume of air inside even a moderately large high poly tunnel, i would not be suprised if one could not simply co2 enrich for periods at night, then cut the enrichment when the heating demand is gone and still have enough co2 to last throughout the daytime.

dehumidification in all likelihood would not be an issue( unless you are growing a forest inside the greenhouse) owing to the interior surfaces of any greenhouse acting as one enormous condensing surface during these cold months. anyone running a greenhouse can attest to how much water runs off the side walls during cold months.

keeping the co2 inside the greenhouse while maintaining the temperatures is another matter though, and idk how they were managing temps without pumping in colder air or using passive ventilation...perhaps they were using heat exchangers to remove heat from the exhaust gas, but i dont seem to recall any of that being talked about.