First, this thread:
I built my brewer out of a small igloo 2 gallon industrial water cooler. I dropped in 2 disk airstones and a 50w aquarium heater set to 75-80. I generally fill a sock with materials, tie it, add the water and start brewing. I pretreat my water to rid myself of chloramines and chlorine too. I usually brew for 48 hours, sometimes longer, but you must keep adding food or the tea dies.
I would be hesitant using a huge bucket (like 27 gallons) unless you are *sure* you can move a ton of oxygen through the compound. If it stinks and has gone anaerobic, do not use that tea!
For instance, with my setup, I usually use about 2 cups per gallon.
Favorite tea right night? molasses, EWCs, oatmeal, kelp meal, azomite, down to earth flower and rose mix, peruvian seabird guano. Drop the last two for flowering. For veg, use alfalfa meal.