Hey, my very first post here. Been lurking for about a year. Just signed up a few months ago so I could see some pics. Anyway, I have been doing the outdoor grow thing and have started an indoor grow (thanks to all of you!!) My question is...can you produce an appropriate amount CO2 from a little vent-free propane heater? The one pictured here is similar to the one I currently have. Anybody have any comments on this?