Ideas for a small DIY co2 provider?

YEAST FERMENTATION A great way to generate extra carbon dioxide is to have a bucket or vat of yeast working away in your grow room. Yeast is a living organism, and is used in the brewing of alcohol. If you supply a colony of yeast with water, nutrients and sugar, it will happily consume them, producing an ample amount of carbon dioxide and alcohol as a by-product. To do this you will need: A 5 liter demijohn (you can pick this up easily online, or anywhere that sells brewing supplies) 1tsp of dried active yeast or a few grams of bakers yeast Warm water 1 cup of sugar 2 pureed tomatoes as a source of nutrients Instructions 1. Fill your demijohn with warm water (but not right to the very top). The water needs to be at least 21 degrees Celsius, but no hotter than 40. This is the temperature range yeast likes to work at, and you will find it is most optimal closest to normal room temperature. If you let it get too hot, the yeast will die. 2. Add your sugar and tomato paste into the demijohn and mix it until it dissolves. 3. Now add in your yeast. 4. Ensure that the temperature of the mixture is maintained. This should not be too much of a concern in a warm grow room. 5. After a few hours, your mixture should start gently bubbling. This is the yeast doing its job producing carbon dioxide. 6. Place the demijohn close you your plants. There you have it, now you know how to make your own basic yeast based carbon dioxide generator. You can keep the yeast colony going by pouring out some of the solution every week or so, and replacing it with fresh water and a few teaspoons of sugar. This will ensure that the yeast has a continual supply of food, and doesn’t poison itself as the alcohol concentration increases. If left without a fresh supply of water and sugar, the yeast will die within a week or two. You can also use a demijohn bung and piping to make the release of carbon dioxide more targeted. This bung (which has a hole in it for the piping), fits neatly into the top of your demijohn. You can then use piping to direct the carbon dioxide directly onto your plants. Bungs and piping can be bought anywhere that sells brewing equipment