The secondary clarifier often becomes the focus of attention for process improvement, leading plant owners to seek performance enhancements by reducing effluent suspended solids (ESS), increasing tank capacity, or both. What causes ESS from secondary clarifiers to be high often is identified incorrectly, resulting in improper remedies. Reducing ESS usually is accomplished by “unlocking” additional tank capacity. Because tanks vary widely in design features and operating problems, prescribing a “one size fits all” design or operation fix will not necessarily correct perceived problems and can waste money.