Most of y'all mention putting the fan over the sump. Any reason I'm not thinking of for placement over the sump rather the main tank? My thinking is that I've got so much more surface area for evaporative cooling on the tank as well as the fact that despite other techniques, my hood doesn't vent well without the fan.

I've not got a radioshack fan (4") that's pretty quiet and on a timer to run from about noon til 5. After a couple of days with the technique I've brought the temp from a pretty steady 82 to 76. that's sure to need some adjusting as summer comes in.

I believe the AC units not being on all the time like this time of year does make a large difference. You get some mid to upper 70s wet bulb temps in your house and you won't be able to evaporate enough to bring the temp down. I tend to keep the house pretty warm in the first place.

I'm also thinmking of getting a thermo couple or something to monitor the temp and have it activate the fan. I've done this with homebrew equipment.

Maybe someday I'll get a commercial chiller. About time to bring another circuit to the tank.