The infill provides the cushioning of your synthetic field. The surface hardness ( measured by Gmax ) is almost always a direct correlation of your infill levels. The infill levels should be measured regularly and compared to the manufacturer’ s recommendations. How much rubber do you need? As a rule – ½ pound of rubber per sq ft. equates to approximately ¼” of infill per sq ft. For example if an 80,000 sq ft. field is low by an average of ¼” – it will take approximately 40,000 lbs or 20 super sacks of material. It is not recommended that you apply more than 6-10 sacks at any one time – so it may take several applications to get the needed rubber down. Please avoid putting the rubber down in wet conditions or you will have a mess.