Originally Posted by Vincent Tran
He spent $25 on a tube(?) and diffuser and 5 on the sugar and yeast.
Oops, you are right. However, that $5 sugar/yeast CO2 won't last for few months.
Couple of weeks top, assuming we are talking about just one bottle. Generally, in a larger tank, something bigger than 20g, the cost is no longer cost effective.