If you have acces to a lot of dry ice, I say go for it. CO2 is emitted as the ice melts. Only problem is you can't control the ppm really, unless you configure a smart exhaust.
I really don't understand why people worry so much about the levels of co2 in the air while the lighting is on. The best indoor crop I've ever had used propane lanterns and a woodstove for co2. The most important thing to know about co2 is that when the lighting is off the plants require o2, and when the lighting is on the plants require co2.If you have acces to a lot of dry ice, I say go for it. CO2 is emitted as the ice melts. Only problem is you can't control the ppm really, unless you configure a smart exhaust.