Looks like I'm about 9 years late replying to this but this is a concept I think about constantly as well. Some of the big questions I have found are: -Is the flow (LPM) strong enough to turn a turbine to generate power? What is the minimum needed for this to be viable? -Will placing a hydroelectric turbine in the system effect bacterial colonization? -Is there a possibility of creating a terraced aquaponics system which will create greater head from which the water to drop and therefore generate a higher volume of energy? Additionally, one potential way to incorporate hydroelectric into the system is through the use of I believe what is called the Kaplan turbine. This turbine would operate as both a filter and through the vacuum it creates, a pump as well. All the while it could also be generating electricity, even if just enough to help offset some of the energy costs associated with running an aquaponics farm. If anyone would like to discuss this in more detail, please reach out to me. I am looking for others to discuss designing and building a proof of concept on this, what I have coined CLAEYS: Closed Loop Aquaponic Energy Yield System.