The Kronus 3 controls temperature, humidity and CO2 in your grow area, and has built in day/night controller to control equipment during those periods using a “Night Only” outlet, and a “Night Heat Output” outlet. The Kronus 3 can activate fans, A/C units, or dehumidifiers using an “Exhaust Fan Output” outlet, and regulate CO2 using a “CO2 Output” outlet. The Kronus 3 has a built in photo sensor to only activate CO2 during the daylight periods. The Kronus 3 does not read CO2 levels; it simply turns on/off CO2 equipment.