I really love the idea of rejuvenating potting mix by adding lots of beneficial microbes! Bravo! Do you ever water potted plants with that tea?
I think I'll add that step to my process for createing new soil from dead clay, for raised beds. Besides adding store-bought manure compost to my home-made soil, drench it with compost tea made as you describe (plus some screened fines from an active compost heap).
If you can borrow or scrounge an aquarium air pump and air stone to aerate it, it's good for the tea. Not vital, since you already have good results with a big garbage can, but it might keep the tea sweet longer than overnight.
If not, and if you live where it's hot, you might try to locate the barrel or bucket in shade where it will be cooler. Oxygen is more soluble in cool water than warm water, and keeping the deep layers aerated is beneficial.
I wonder if some "continuous" process would provide air as well as keep the exponentially growing aerobic microbes always in active growth? Say, use a 5-gallon bucket and every day or two take out two gallons of tea and add two gallons of water plus a small amount of manure?
At that rate, you could afford to use it for most of your watering or slosh it on leaves frequently as some recommend.
