There is no question that the CO2BOOST BUCKET is the best of your options. Don't let the price scare you, it is absolutely worth it. I have been growing in a 5x7 tent for 4-5 years and all I use is CO2 Boost. Its all organic/natural, quiet, totally safe to breath and requires no heat/burners. You simply plug it into the timer to turn on an hour before the lights turn on (to let the CO2 build up) and thats it!!! It lasts 3 months or more from the time you open it, you never have to do anything (like refill co2 tanks every 3-5 days=gas$$$). The Boost Bucket is definitely worth the price and will increase yield/fruit by AT LEAST 30%. Wait till you first offer it to your seedlings, those little babies stand right up!!!