Trapper
Rocky Mountain...High
what are some cheaper CO2 options?
Well, there are a bunch of DIY techniques that are very cost effective...I can't speak to those as I'm lazy and buy Exhale Bags or Boxes of Mushrooms...
http://www.myco2bag.com/wp/
http://www.exhaleco2bags.com
I used Exhale bags on my first grow but the MyCo2bag boxes are an improvement in that they aren't activated until the consumer "activates" it.
The Exhale bags are activated the moment they are produced so you pay for CO2 expended while it's waiting on a shelf to be bought....
But like I said....many youtube & other instructional vids and threads on DIY (or "Redneck") CO2 generators.