I fed my one of my plants club soda (no sodium added carbonated water) for a week. I didnt spray it, i poured it into the soil. The results were rapid growth and with the combination of LST and FIM the thing looked like a bush that was tied in a knot. The leaves were also a darker green that the others and they were a lot tougher. Once i stopped. The growth spurt slowed down to its normal rate and is still larger than the others.
For a home made CO2 genrator, get a nice big jug. I use the 1.2 gallon juice jugs you get at those warehouse shopping clubs. Fill it about half way with water that is around 110 degrees. Any warmer and the yeast will die. I then added 1/2 cup of sugar and 1 tbs of activated dry yeast. I have that in my veg chamber. Every couple of weeks, i pour out half the water, add more, add more sugar, and a touch more yeast, then let it do its thing.
It doenst produce much, of course the larger the container, the more gas would be produced, but every little bit helps right? Races are won in 100ths of a second. If this small bit of effort produces an extra gram per plant, then im ok with that.