Well, Bob Hemphill's favorite way is to soak compost/earth worm castings into your water bucket w/ a mesh bag. Basically you extract the microbes from the quality compost into the water. The trick is to only soak for 5-10 minutes and water your plants with it right away. The microbes will die quick in the water. You can also collect vegetation in your yard (as long as no one sprays glyphosate around, and no walnut trees near) and soak that in water. Soak the vegetation in 5 gallon bucket for a few days. Then, you add an airstone for the last day before you use it. The last suggestion is to buy some malted barley or any type of malted seed. I also do this with chickpeas.