I am using a poor mans CO2 set up with one gallon of warm water with one pack of yeast mixed with 1 1/2 cups sugar with a hose running to my plant tank. I also took a cheep plastic cake lid and made a clone dome. and burred it in rocks. I am using river pea gravel from Lowes 40# bag $ 4.00
The the timer kicks and the tank floods the water creates a seal and saturates the leaves in CO2. the timer kicks on every hour for 15 minutes.