| I saw these previously demonstrated at a local swap, and for 20 dollars it's one of the cheapest ways to get massive amounts of flow. I was really stunned with what they can do. Three 600's with these and anything under about 75 gallons should be way above your needs.
There's another company i saw that makes these same things, only there's come with a hanger attachment for suction cups/magnets. I'd recommend these as a quick and easy solution to flow problems. | 
