Just run multiple pumps and stones. Also, I use aquarium maxijet 1200 pumps for saltwater tanks. I had a reef tank at one time and all kinds of biologics can go thru those things, otherwise....a reef tank would die.
Oddly enough using a deep sand bed and live rock as a filter for saltwater is very similar to maintaining biologics in soil. I am not saying they are the same, just related.
Also, I use a ten gallon rubbermaid food storage container (20 gal trash cans at the HD are $15-19 just fill it up halfway) The pumps can be ordered on the net or found at local fish stores, not big name places but any good fish store. should cost no more than 30-40 per pump, they do make smaller outputs for less. As for the air pumps, go to wally world and buy two, get a splitter and run four stones. Plenty of air.
Not only do those pumps circulate well but you can attatch 3/8" I.D. hose and pump it out into your watering can.
Sometimes I make the ten gallons strong and dilute it with hose water 50/50. The stuff at the bottom is like silt and I pour that around my beds. When I get my cam back I will do a brew and try to take some step-by-step of my own method. You gotta remember, its organic so its hard to screw it up. I have yet to overfertilize with the organo tea. BTW, you can see the resluts of my methods in my outdoor organic lst thread.