I would go with Hydro Innovations HydroGen Pro, i used to run bottled co2 on a sealed 5k garden, (50 pound tanks at that) and was running through 2 tanks a week and it began to be a hassle everytime id come into my growroom the tank would be empty and my co2 levels down not to mention the price of tanks co2 and regulators you basically are breaking even for what youd pay for a nice burner, ever since i came across the water chilled burner (which basically runs on the same concept as a small hot water heater), with this burner you can either cool it by circulating water through the unit, a small chiller, and a reservoir. Or run it drain to waste straight from your grow locations cold water lines through the burner and expelled into the plumbing as needed ( which is the most effecient route to go IMO) i also hardlined my burner to the natural gas line of my location so i never have to refill a propane tank. i love the convenience of this product and honestly would put my name behind it anyday its saved me a handfull of time. ALSO remember that co2 is more dense than oxygen and always falls so place your burner high and keep fans circulating above your garden and from the floor up. hope that helps