My honest answer would be no powerheads; instead do a closed loop with a nice external pump. I personally don't like powerheads in my tank; they look lousy, they're constantly getting crudded up, falling off the suction, adding heat and stray current, etc....If you don't have them yet, consider the closed loop option. you can easily plumb it without drilling your tank; you just add a "priming" tube to your plumbing. There's a guy in Forth Worth (I think) named Mark Levenson who posted plans for this on his website.

Most important, WELCOME! to MAAST.

In my old 45 breeder, I had 4 mj1200s plus an iwaki 700gph return pump. That was ALOT of flow, but everywhere you looked in the tank there was a powerhead, lots of extra heat, too much linear current, constant maintainence. Now iin my 100 gal I have a closed loop with a 1200 gph iwaki and 2 sea swirls; it's much better.