Bought a 476gph Tunze Nanostream 6015 and cut out the inside shroud per online instructions. This thing gotta put out about 750gph now. Much better than a Koralia for only $38.
http://www.ultimatereef.net/forums/showthread.php?p=1890178
http://www.ultimatereef.net/forums/showthread.php?p=1890178