Powerheads? Think flow, Flow, FLOW! In my 210 I currently have two quiet one 6000 (one for each return), 2 Seio M1100, 2 Hydor Koralia 3, 2 Hydor Koralia 2, and 2 Maxi Jet 1200. You want a chaotic not laminar flow in the tank. The old rule of 10 to 15 x per hour turnover rate is out the door. Try more like 25 to 30 x per hour or more. That much current help clean the tank, removes wastes from sessile invertabrate as well as brining them both food and oxygen. In my system with 8000 gph
turn over and I stll have troubles with a few settling areas. Just get the flow up there and your tanks will show incredible growth rates.