I added CO2 injection to my fish tank today, this is to help the plants grow. I added 500ml of water to a 2litre softdrink bottle, then added three teaspoons sugar and one teaspoon of bakers yeats. I wanted brewers yeast but the store didn't have any.
Within 15 minutes with it on top of the light on the tank, the warmth had the yeast cranking, I am getting a bubble of CO2 every 1.5 - 2 seconds, I am feeding it in to the pick up tube of the filter pump to disperse it through the tank.
This should help the plants grow quicker..