I've been using co2 enrichment for some time though I only recently really got it correct.Without the correct environment it'll do little good.You need a minimum 50 watts sq ft of HID light,air conditioning or a way to control temps, a dehumidifier and oscillating fans pointing upward ideally.You want temps at the canopy to be 85 degrees,this is most important and was really hard for me to swallow,it isnt anymore lol.A lazer thermometer is really a good thing if you're serious about co2 enrichment because you wont get it without spending a grand on equiptment anyway.I use a green air cd-6 and used a cyclestat for years(timer for frequency and duration of burn),that was a big mistake.A controller is almost a must to get real enrichment,fluctuations of more than 300 PPM arent desired and thats what happens with a cyclestat.A controller kicks in at a certain PPM instead of it being timed,huge difference!The cap PPM-3 for 500 dollars is the cheapest,period.It works well.Another thing I did wrong was use a dual hose portable thinking with the intake hose through the wall into the room next door,I wouldnt have any problem.Another big mistake,which took literally years to discover.I was somehow shooting my co2 right into the attic,the intake hose drew air but so did the unit,obviously.As soon as I deleted it my co2 stayed in the room,window ac's dont rob you of co2.When you get it correct you absolutely know it,they'll eat more grow faster and finish 10 days ahead on a 60 day strain.Its amazing,my yield also increased 25% the first time I got it right,I do perpetual grows of the same pheno's so I know what to expect.Paintball,yeast and all the other ideas just dont really do squat,its a difficult thing to get correct it takes time and definately good equiptment.