I can assure you that co2 will do a great job. Much better than before. And you dont need to spend a lot of money. You will need a 10L bottle, 2kg sugar and about 10g of yeast. You will fill the bottle with 5L of hot water (arround 35C), you add the sugar and the yeast and shake a little. Then you make a small hole on the cap of the bottle and you place a long (about 1 meter or more) rubber tube in it. You make sure that the bottle is air-tight so that the co2, that will be prodused, will only escape from the rubber tube. After 20min the mixture will start to bubble and CO2 will be prodused from the reaction of the sugar with the yeast! The best way to place the edge of the tube, is above the plants, because CO2 is heavier than air and will always go down. If the air circulation is good, the CO2 will spread all over and will feed the leafs perfectly! You now have a fine CO2 system which will be working for about 2 weeks. After 2 weeks you have to empty and refill the bottle with hot water,sugar and yeast!
I hope that was helpfull and not confusing because of my english.
