The aquarium or terrarium light systems simulates rising and setting of the sun. A housing contains two lamps, one variable lumen output for graduated light output and the other for full ON or OFF lighting. The light fixture contains a timer/dimming unit to variably increase power/voltage to the first lamp (variable output) and then to supply full ON power to the second lamp. The timer turns ON-OFF the second lamp late in the sunrise cycle and then early in the sunset cycle.