How much CO2/W of light do plants need?

Does anyone have any thoughts on using a sealed and cooled space that doesn't vent externally? CO2 would be artificially supplied, but how much? Does anyone know a plant's rate of respiration?

CO2 Calculator - Greentrees Hydroponics This is the coolest thing I've found and the recommended level is 1500 PPM. Good luck

1800 is what i hear

don't forget to factor in 300ppm co2 in the air already... Co2 injection should be injected in a semi hot room 85-90 deg for the plants to soak up a good amount..

You know that is what i have always heard. When you watch Remo the "Urban Grower", he states 78 degrees, 40% humidity and 1800ppm Co2.

hmmm. Hot or Not?