CO2Gro C1 CO2 ControllerCO2GRO C1 CO2 Controller with Internal Sensor for Grow Rooms Take precise control of your grow room environment with the CO2GRO C1 CO2 Controller, available at Holland Horticulture. Designed as an affordable and reliable solution for CO2 monitoring and dosing, this controller allows growers to fine tune CO2 ppm levels to maximise plant growth, yield, and quality. Accurate CO2 Monitoring with Internal Sensor The C1 CO2 Controller features a built in