Investigations of the presence of granules for three flow-through facilities were conducted due to their low SVIs and exceptional effluent qualities. These facilities were designed using different biological nutrient removal configurations and without the use of external selectors such as hydrocyclones. But they all share one common design feature: compartmentalized selector zones with a high food-to-mass ratio in the first compartment to promote a feast-or-famine condition. Results showed that the percentages of particle size larger than 0.2 mm found in these facilities were higher than a well performed facility equipped with hydrocyclones. This proves the importance of internal substrate selection and the benefits of granules to improve performance.