Find high quality Environmental controls including cycle timers, temperature controllers, humidity controllers, and CO2 controllers from Solatel & Sentinel - the Environmental Conrtol Specialists. Promote a healthy environment for your greenhouse or grow room using a high quality CO2 controller. Increase your crop with the use of a cycle timer. Cycle timers/controllers help maintain the indoor environment of your growing area. These cycle timers are an easy and flexible way to maintain the optimum temperature, humidity and CO2 in your growing area.