Environment / Carbon Dioxide (CO2)
Carbon Dioxide is a key part of photosynthesis. Plants essentially do the opposite of humans, they 'breathe' in CO2 and release oxygen. If CO2 levels are increased then the plant can increase production resulting in accelerated growth, more resistance to heat and overall larger yields. It is important to remember that to see the most out of the yield increasing benefits then the rest of the grow room environment must be perfect.
The amount of CO2 in a room is measured in ppm (parts per million), and the ideal amount is around 1500ppm. Some growers prefer to run 1500-2000ppm and higher to see even greater effects than normal. To do this the grow room temperatures need to actually be higher than normal(around 80-85F), plants will use more water and nutrients and will have huge yields!