I had a similar question some time ago and here is the thread, hopefully it helps.
http://www.aquariacentral.com/forums/showthread.php?t=146835
my biggest turn off would be the strong current (smallest I found is rated at 530gph)and noise (I remember that thing being pretty loud). but if you reduced the flow like jaysen mentioned and had your tanks in a basement or run the filter when you are not home it would clean your water up real fast.
http://www.aquariacentral.com/forums/showthread.php?t=146835
my biggest turn off would be the strong current (smallest I found is rated at 530gph)and noise (I remember that thing being pretty loud). but if you reduced the flow like jaysen mentioned and had your tanks in a basement or run the filter when you are not home it would clean your water up real fast.