A pool cleaning robot can include a main housing configured to be submerged in a pool. A propulsion unit within the main housing can be configured to move the pool cleaning robot along a pool surface. One or more germicidal light sources, configured to disinfect at least a portion of a pool surface, can be positioned on a bottom of the main housing. A power unit can be configured to power the propulsion unit and the one or more germicidal light sources of the pool cleaning robot.