First of all I’d like to make it clear that most aquarium air pumps don’t produce enough air to use in a container larger than 1 gallon when considering making an aerated brewer. So don’t even try the 5 gallon pail with the aquarium pump idea everybody is passing around. You need a minimum 0.05 CFM (cubic feet per minute), open flow of air and an optimum 0.08 CFM per gallon (US) or higher to make aerated compost tea (ACT). ACT should have the DO2 sustained at or above 6 PPM. Generally, aquarium pumps produce around 0.02 to 0.16 CFM. Another generality is that 25 watts of power usually produces 0.75 to 1.0 CFM in diaphragm air pumps. The wattage is usually marked on the pump which will help you figure out the approximate output. I’ll cover more on air pumps later.