Example embodiments of the present disclosure are directed to a robotic pool cleaner and a control system of a robotic pool cleaner having an optical sensor positioned relative to an intake pathway of the robotic cleaner to monitor a flow of material through the intake pathway. An output of an optical sensor of the robotic pool cleaner can be monitored by the control system of the robotic pool cleaner to determine whether a detectable level of debris is flowing through the intake pathway. The robotic pool cleaner can perform one or more operations in response to a determination that a detectable level of debris is flowing through the intake pathway based on the output of the optical sensor.