Day Night CO2 Monitor and Controller for Greenhouses Controls CO2 in greenhouse, grow room. Built-In light sensor allows CO2 enrichment only during daylight hours. Piggy back plug allows for control of CO2 generator or regulator (sold separately). User can set desired CO2 level for different plants. Easiest CO2 controller to use in the industry. Accurate CO2 Generator Control Photo Sensor that Turns off CO2 at Night Large LCD digital display that indicates CO2 and Temp Easy to use functionalities IP54 enclosure NDIR CO2 Sensing Technology Non-UV Emitting LEDs