I use a bucket (2gal, 5 gal) and suspend a 1 gal paint strainer bag into which I put a mashed up baked potato and some leaf mold soil (although I use worm castings instead, but similar outcomes). Add a hint of sea salt and fill with non-chlorinated water, cover and let it sit near your plants so you cultivate the microbes in the same environment you'll be using the stuff in. In a couple of days you'll get some bubbles that show the microbes are hard at work. At the peak of the bubbles is the peak of the population of what you're cultivating and that's when you use it. Of course your environment will dictate how long that takes so you'll need a few rounds to dial it in.