For flow in a tank that size.I'd look at a couple of these.
Hydor Koralia Circulation Pump/Powerhead UL
I think 2 of the Nanos would be plenty of flow.
As for care of those corals.About all they need is good stable water quality,some flow,and light.
2 powerheads in a 10 Gallon tank; both at 400GPH? That seems... high doesn't it? :?
Sorry, it just seems like a lot to me, but again I'm new. So if everyone else agrees on that, then that's what I'll get. :D