I couldn't quite follow that either, my best guess is that the 500gal returned to the stream puts the appropriate organisms into the water, and by now it has reached a steady state where the introduced organisms over the last x days are also consuming fuel oil in an equivalent of 100000gal of water.

500 gallons per day is filtered through the greenhouse and then applied to the restorer in the canal.  The restorer itself floats on top of the canal and the roots of the plants in the restorer filter an estimated 100,000 gallons of water in the canal per day.


Solar IS Civil Defense