OK, just for the sake of debate,
and this is all subjective information at best....
1,000 GPH for a reef tank should be more than adequate.
I suspect the real problem is how you are delivering that flow into the tank. Many people use the fancy hyloc wedge-shaped devices for their final output. However, these devices rob at least 1/3 of your water velocity, by my estimation. This is very inefficient.
Reefmeister's recommendation:
1) ditch the hylocs
2) divert the 3/4" single return line into two seperate lines via a 3/4" wye connector: (closest to final output as is reasonable)
http://www.plumbingworld.com/pvc.html#wye
3) reduce the dual 3/4" lines into 1/2" and route to point in different directions into the tank.
4) Acquire two 1/2" versions of this device for your final output "nozzles":
http://www.aifittings.com/whnew10.htm
(also available at Home Depot in the electrical isle, model #NMLT5090-1 or SKU #1899706242-0)
5) Experiment by articulating the two devices in different directions to obtain the best overall turbulence for your tank.
These liquid-itght connectors are completly non-restrictive, non-metalic (discard the metal lock ring, of course) and non-obtrusive from an aesthetic perspective because of the neutral-grey color (tends to "hide" the device for lack of a better term, though coraline algae will eventually cover the device anyway)
Reefmeister uses four of these devices inside his 90 gallon reef(net 2,000 GPH) and it is literally a storm inside the tank! (I have to cutdown a bit to obtimize)
There you have it; no ugly powerheads, no closed-loop, no extra pumps, etc. etc.
That's my recommendation and I'm stickin' to it!
Good luck!
