Co2

I am using Jethros closet plans and all seems well so far. Would setting up a yeast/sugar do any good for CO2? I was thinking on using a milk jug or a 2 liter bottle with a small hole in the top. I am looking for the cheapest way possible. I have yeast and sugar as it is, I have spent enough money this weekend and dont really want to spend any more.

Also, does CO2 raise or lower the temp? Right now the temp is about 84-85 with lights on, I have not checked what it is with the lights off. TIA

add the co2 it will help plant an bud growth...use the 2 gallon jug an active yeast

Any good recipes anyone knows of? I have seen the same thing used for fishtanks with good results but was looking for something that would be more ideal for this situation.