The RockWater suction pipe secondary clarifiers are designed to provide quick and uniform removal of return activated sludge (RAS) which utilize collection pipes located at multiple points along each arm. Suction generated by a differential head developed from the partially submerged return sludge well located at the center of the clarifier. Each collection pipe is equipped with a return flow PVC valve that controls the rate of sludge return and provides a visual indicator of the RAS. Every pipe discharges into the rotating center return sludge well, then by gravity exits through a vertical steel pipe located inside the center pier. The size and quality of pipes are selected according to the RAS flow rates.