i just did CO2 and if you have a photo sensor you still need a monitor to measure CO2 ppm because if you have too much CO2 can hurt your plants. the thermostat really does nothing...you need a timer on your fan~off during light hours and on at dark...if you have your fan kick on just for temps then you are wasting your CO2:jointsmile:

you can still feel cool bro...you are right you need 2 timers...1 for your CO2 generator and 1 for your fan...i know you have an AC in your room that is where your thermostat comes in to keep your temps in check and not waste CO2 :smokin:
stra8outtaWeed Reviewed by stra8outtaWeed on . DIY co2 controller if you own thermostat. i had this idea to build a co2 venting controller. items needed: -light detecting outlet - about 20$ -thermostat you plug in your fans to the thermostat and have them go on and off. you also have a light plugged into the thermostat one that goes on outside the grow room. a small light the smallest cfl you can find. plug your co2 into the light detecting outlet. now you can kind of see how it would work. when the light goes off and fans too, the light detecting outlet would turn Rating: 5