You can make your own Co2 bottles..

You only need: some dry active yeast, some sugar and warm water!

Step 1, Put one liter off water in a bottle, then add 1/4 teaspoon off dry active yeast, then two cups of sugar; shake well, EVERYTHING must be disolved.. When you have done that, add ½ a liter of warm water shake until disolved, again...!

Put two or three of those bottles in your grow room, and you will see improved growth..

P.S. you need to see some bubbles in the water to know if it's a succses...!

Razta Kaze gave me this recipe!