its actually a jello co2 system. http://www.plantedtank.net/forums/diy/9916-jello-co2-thread.html but i tweeked my with just random measuring and loading.. but i personally belive adding more sugar to the jello will give you a bit more co2.. and its been bubbling for a good 2 months with a bit if slowing down... the jello is now about 1/4 in the bottle
you can actually pour out the old yeast if you refridgerate the bottle to stiffn the jello and then pouring out the old yeast