I have had my aquaponics set up going for about two months now. I have 109 tilapia in a 270 gallon tank. In the tank I have a 400 gallon per hour sump pump that pumps continuously. The water loaded with fish poop goes into my grow beds that are filled with 3/4 pea gravel. My grow beds are 10 feet long, by 3 feet wide, by 1 foot deep, and I have two of them. They fill with the fish poop laden water in about 45 minutes and then it all siphons back into the fish tank in about 5 minutes, and then the filling process starts again. This process of filling and draining continues automatically. The pea gravel filters all of the fish poop out of the water and the fish tank stays nice and clear and the ammonia and nitrite levels near zero and the fish grow like crazy. It seems crazy but I just broadcasted seed into the 3/4 pea gravel and I have spinach, lettuce, beets, parsnips, and tomatos and they are growing incredibly fast. They really like the nutrient rich water that comes from the fish tank. I will harvest a bunch of spinach and lettuce tomorrow and in about 2 more months we will have tilapia cooking on the grill. I have had so much fun learning about aquaponics and building the system. I have my present system in a 10×12 greenhouse that I built. I am getting ready to expand my system using a 1000 gallon above ground swimming pool that is 12 feet in diameter and 3 feet deep and I will have 6 grow beds to go with the fish tank. With these two systems I will be able to harvest 1000 lbs of tilapia fillets and lots of vegetables of every kind each year. It is a good thing I have lots of kids and grandkids to help me eat it all. I was reading last night of an aquaponics system set up on 5 floors in an old warehouse using all grow lights that covered about 3,0000 square feet of floor space and they made a million dollars a year in profit selling fish and vegetables. Whooooeeeee, I am not going to do that but is fun to think about.