I have a cap gen1 propane generator.You either buy expencive meters and monitors or like I do. My gens on one timer(digital) the light on another timer, exhaust fans on another timer all digital. Mount the generator up twards the ceiling as the co2 is heaverier than air so it falls.go to this sith and culculate how much co2 you need for your size of room CO2 Calculator - Greentrees Hydroponics . After you figure how much you need for your room and howmuch the gen puts out you set the timers up accordingly. I have mine set at top of the hour my fans shut off and 1 minute later the co2 starts and runs 8minutes the 2 stay off until 30 minutes after top of the hour giving 21 minutes for the co2 to absorbe and fans come back on untill top of the hour startes againe. get a ppm tester and ckeck co2 every now and then.PPM you should add about 1200 normal air has about 300 so togather would give you 1500ppm.