use 12 cups of warm water, 2 teaspoons active yeast, and 1 1/2 cups sugar. mix this in a gallon milk jug. drill a hole in the lid and poke a piece of airline tubing into it and seal it with silicone. Co2 is way heavier than air, so you have to run the tubing up above your canopy. to get enough Co2 for say a 4x4 tent, ull need a 5gal bucket with 5x the mixture. i first run my tubing down into the bottom of a sprite bottle, filled halfway with water and another tube coming out of the top of the bottle going to the top of the canopy. i use the second bottle so i can monitor the amount of Co2 bubbles. when i 1st mix it, it makes 1-2 bubbles every 2-3 seconds. once it slows to about 1 bubble every 6-8 seconds, i replace it, which is about every 2 weeks. i use the 1 gal for 18"x30" grow area.