Soil compaction is one of the primary reasons that grass won’t grow to its potential. Whether the result of mowing, foot or pet traffic or irrigation; soil compaction restricts the movement of oxygen, nutrients and water to the lawn. As a result, the grass grows slowly and poorly and soon becomes susceptible to drought, disease, and insect damage. [http://www.lawnandlandscape.com/article/ll-031815-aerate-aeration-equipment/]
Aeration equipment removes 1.5 to 3 inch plugs of soil to allow moisture, air & nutrients down to the root zone. A double aeration takes the form of two passes in opposite directions. A triple aeration adds one more pass with the aerator, multiplying the opportunity for a successful lawn.