I've seen some strains that do not respond well to co2 in terms of the effect it has on trichome production / aroma; I don't know whether this is because the enhanced co2 changes the nutrient requirements or amplifies imbalances that might be present, but I've have definitely worked with strains that loose some shine running co2 (but show significant yield increase).
My advice is to introduce co2 in a graded way, stepping it up each week and peaking at 1500ppm in week 5-6 of flower for ~8-9 week strains.
Originally Posted by darrmann
In my opinion and many others you cannot do without co2 ,especially in a sealed rm. Co2 levels drop to around 300 in about 2 hours. plants will die if under this. they say that around 1500 is what you want to keep it for optimal use. I have 2 rms roughly 10x12 and use it and get great tasting buds. You can buy a regulator for $150 and a bottle for$75 with $15 refills. My small 20# bottle lasts about 2 mths.
Wow your 20# lasts 2 months? My room must not be truly sealed, because my tanks last only a week (10' X12' room also, aircooled).. I guess the aircooled ducts and lights are probably not truly sealed and drain tanks..