i use 1.5 litre coca-cola bottle,1/4 teaspoon yeast and 1/4 teaspoon soda powder + 2 cupful sugar.i pour the sugar m soda powder into the bottle using funnel which filled with warm water m shake it until most of the sugar dissolved.then i add 1/4 teaspoon yeast into it without shake it.

the 1 way valve has a switch that u can control the amount of gas that flow out through airstone while using it in air pump.
am i right??????