For what it is worth this is how I cool my tank when the weather gets warmer. The setup for 2 fans cost aprox. $20.00 if any one is interested in the details just drop me a e-mail.
I agree falling in would be a bad thaing. I have notched out the ends the one set of fans should be going perpendicualr to the sump not on an angle, I was just a little lazy there. With the PVC being notched they can not fall in.
