heres a link I found that tells you several easy ways to make Co2... Gases - Science Is the Eggshell way effective? how many eggshells should I put in the bottom of a 1gallon jug? then how much vinegar should I put in? say I buy yeast tomorrow. If I go to the local food market stores, what type of yeast and vinegar do I need or does it not matter. how long will the co2 be activated in a 1gallon jug and how many times should I expose my plants to this process? How can I tell when they have had too much Co2? any reply's appreciated. I have a 7foot tall x 3 x 4 foot box inna closet with decent ventilation. If I put two Co2 jugs at either end of a bubbleponics system (6 plants) will they take in the C02 fine, or should I just put one jug in at a time?