Abstract: A spa control system controlled by an infrared beam. In one implementation, the spa control system has a sender device located at a target sender area of spa shell, and a receiver device located at a target receiver area of a spa shell. The system includes receiver electronics associated with the receiver device, in which the receiver electronics are configured to transmit a signal when a path of the infrared beam is interrupted. The system also includes one or more control units of the spa to receive the signal, and to adjust a function of the one or more control units according to the signal received.