Alright, I'm a complete and utter noob to air pumps. I need to get an air pump to brew 200 gallons of tea at a time. I know that sounds like a lot, but many people use much more in smaller hydro systems. I have Four barrels, Each one holding 50 gallons. At minimum I want to be able to run two 6" air stones out of each barrel (Minimum, preferably 4 airstones).
There is a thread somewhere on here about DIY vortex brewers using 5 gal buckets that im sure could be modified to 55 gallon drums and relatively cheaply too.
Shoot for 1 lpm per 1 gallon of water for actively aerated compost teas, agitation and aeration need to be intense to get the best teas.
An eco air pump with a couple stones is hardly going to get you what you need.
Current Culture H2O has Alita and Hi-Blow air pumps as well as some pretty cool diffusers, I bought a brewer from them several years back, it still kicks ass.