Chapter emphasises the importance of air exchange in the grow room
and the benefit of oxygenated nutrient solution, a diagram and a chart
are employed to express this importance, as well as a 3 dimensional
CAD rendering of a plant's needs. The chapter concludes with temperature
and humidity control via extraction fans with photography of extraction
fans, fan filter combinations, silencer, and thermostat controller.
Conclusion is drawn at the end of the chapter summarising the importance
of this commonly misunderstood arrangement.