I think you'll be fine with some fans. I highly reccomend the 4" fans from Radio Shck that run on AC, so you don'tneed an adapter like you do with the DC computer fans. They move a TON of air, and are really quiet. They're also $25 a piece, but totaly worth it.
I assume these are going in a canopy? If so, remember to have the fans push cold air INTO the canopy instead of pulling the warm salty air out. It's hard on the fans, and will wear them out quickly. You might also look into one of those cheap 7" clip on fans they sell at places like Wal-Mart. I have one of those blowing on my
sump, in addition to several of the Radio Shack fans in my canopy. I have 2x400 over a 120 and it keeps my chiller off most of the time.