Quick update, I am up to 16 fish (300 gal tank, 51 sq ft of media grow bed and about 10 cubic ft of lettuce continuous flow beds) they seem to be doing well. The only chelated iron that my hydroponics store had was liquid seaweed with iron, is that ok to use? I haven't done anything with the pH it is running at 8.0, ammonia is 0.25, nitrite 0, nitrate 0. How long does it take for the nitrates and nitrites to show? What should the levels be?