Cooling is increased many times with evaporative cooling.
So have the air blowing in and aim it at the fasted moving surface water
in your tank.
Some 5" ducting and a flange (that suits most fans) and you can have the
fan where ever you like and still hav ethe air blowing on the water.
This works very well and has saved me heaps on chilling costs over the
years.
A single 5" fan and some ducting keeps my enclosed 4x2x2 tanks with over
1000w of MH in each under 30 degrees C when air temps are in the 40s, so
that's a 10 degree drop in temp (not including the extra heat from the
large wattage lights (one bulb is 1000w and only 6 inches above the water)).
The humidity here gets quite high too (which inhibits the evaporative
cooling effect) so if your area is less humid you could probably count
on even more cooling than 10 degrees.
Good luck.
Simon

Splitskull wrote:

Paul... depending on your temp in da room you will heat your aquarium quite
a bit.

"PaulB" wrote in message
...


I would mount them blowing in. The reason is that they can blow directly
onto the surface of the water, and they will last longer, being subjected


to


less humidity and salt water mist.

On my new 180 I plan on mounting them one each end of the canopy , blowing
in horizontally (2 Icecap variable speed fans).

If my canopy was constructed differently, I would put them in the top,
blowing down onto the surface of the water.




"MarkW" markwco*remove to wrote in message
. ..


I have a 125 gallon tank with Compact Flourescent light underneath the
canopy. I have purchased a couple small fans, maybe 3 inches diameter
or so. I plan to plug them into a timer and run them during the day
when the lights are on. My question, what is the best way to mount
these?
I assume one towards each end but do you want them blowing into the
canopy or out of it or one one way, one the other?
Most of all, hwo do you physically mount these under a canopy? I know
I'd mount them towards the back but they are a square with just black
plastic and a screw towards each corner holding the front onto the
fan. I just can't figure out if I need a bracket or what to use.
Thanks for any help.