for those of us with little to no money, my yeast, sugar...sedtup is the cheapest method. I know it sux compared to a commercial co2 maker but I live down in this basement with my plants and prefer not to die from c02 poisoning! what little my system generates may indeed be laughable but it can't hurt! it's better than nothing to each his own, i'll still grow my plants just may not be as bushy as yours, but their mine and I grew them and that;s what counts.