Im running the newer koralia evolution power heads.
I have nothing bad to say about them.
Im using two of the 1050gph models
Easily the quietest power head i have ever run. Or quietest pump for that matter.
Only uses 5 watts of power.
Great price as well...
These are plug and play right out of the box.. no hassle. They suction to the side of the tank, as well as have a magnet that goes on the outside of the tank.. they wont be going anywhere.
I thought they would blow my arowana around, and turn my tank into a whirl pool, but they dont. The aro can swim directly in front of them, and is only slightly effected, but he doesnt seem to mind it. They put off a large flow of water, but not a jet stream like some powerheads do. So while they keep the water ciculated, they dont blow everything around. Very well distributed flow, which is not easy to get in long and wide tanks.
I got mine here:
http://www.aquariumsupplies.ca/koralia-evolution-1050-p-5672.html