Dave,

Fans are obviously the first step. I'd be uncomfortable with 84. You could start even with a clip on fan or two, found at Walmart, Walgreens, etc. Otherwise, most go with a 3-4" fan (either DC or AC) only the likes of Radio Shack's stock. Those you'll have to wire yourself, though. Just try to get more airflow across the water surface.

There's been many discussions lately on temp and cooling.

I have been able to keep 75-77 recently running a small handmade cooling tower. There are a lot of issues involved. Lights, water volume, humidity, internal heat sources like your pump or sterilizer.