increase yield?

Hey everybody, Does anyone know if the homemade Yeast+Sugar+Water Co2 Generator really helps, and is it worth it? Increase Yield ? Anyone have maybe an experimental grow that can compare a plant that had the Homemade Co2 and one without, and see each's yield? Ex: Size of Generator, Size Room, #...

I am a newer grower now starting my second grow. I have a 4 inch banana kush clone in a 5 gallon hydro system. I only have 24" of available space (bottom of plant to top). I am going to 12/12 when its 6-8". Any suggestions on how to increase yield.