I have the ubiquitous baker's rack system as you know.....I plied them with two 48" WalMart florescent fixtures for $10.00 each and am using some type of Phillips plant lights T 10's that do not throw of much heat.
2 rows of lights for a total of 4 bulbs per shelf with 4 shelves utilizing the lights for a grande total of 16 bulbs per rack!
Even with all those ballasts, I really don't get a big temp increase. My tiled concrete floor stays @ 72F and my ceiling temp is @ 78F. Ambiant room humidity is sometimes 50% !
The fixtures are flex tied to the bottom of the wire racks and there is a very interesting thing at work here...when tied tight, there is a nice 1/2 inch space between the top of the shelf and the fixture, creating a nice heat dissapation pocket.
But to answer your question, I use those fans for everything:
- a little cooling
- directed on the vivs for air exchange even with a glass lid
- directed on floor spills to speed evaporation
- to stir up FF in or near vivs
you name it....they are that handy.
PS...I have a nice Sony DSLR camera....maybe it's time I learned how to use it so I could post some picks of my frogs and vivs and racks...