I know a marijuana grow room can get much hotter when it's using CO2 but hot can a marijuana flowering chamber get when it’s using CO2?
CO2 generally produces a rate of photosynthesis that is much faster than normal (as long as the cannabis plant receives light, water, and nutrients in sufficient amounts). The photosynthesis rate isn’t affected substantially by temperatures in the range of 65 to 90*F.
On the other hand, temperature does affect the metabolic rate of the marijuana plant, which is the rate at which the cell (and ultimately the plant) functions. Similar to cold-blooded animals, warmer temperatures produce faster life processes like conversion of food to energy and tissue growth. If the marijuana plants don’t have CO2, the best temperature range for cannabis is from the high 60s to the mid-70s. In this range, metabolism and plant growth are balanced adequately. When temperatures dip below 68*F, the rate of metabolism reduces, which increases the storage of sugar (vital for plant energy). But, the growth rate also slows.
At temperatures higher than the mid-70s, the metabolic rate increases, forcing the plant to use sugars on metabolism and less for creating tissue. Of course, this weakens the rate of tissue growth substantially.
If the air is enriched with CO2, sugar production increases dramatically, making the marijuana plant “thirstier” and “hungrier” for more water and nutrients. The plant could also use more light. Increased temperatures in the range of 80 to 85*F increase the plant’s metabolism, but it also increases the plant’s rate of tissue growth. Because the plant is producing more sugar, there is enough to go around for both tissue growth and metabolism. This ultimately results in faster tissue growth.