Dissolved oxygen is a critical resource to plants for completing photosynthesis and healthy growth. While oxygen is technically available to plants through their leaves, oxygen is actually most readily absorbed through the roots, and a plentiful supply ensures optimal growth.
The presence of oxygen in the nutrient solution also inhibits the growth of pathogens produced by anaerobic bacteria In addition, the motion produced by aeration ensures that the nutrient solution remains uniformly mixed and no significant temperature variations develop within the reservoir.