Physics Question
 

I'm building a canopy for my tank and am installing two Ice Cap 4" Canopy Fans. Which is more efficient for cooling: drawing the warm air out of the canopy or blowing air on to the surface of the water?
I'm thinking drawing air out would be, but I'm not sure. Suggestions?

I vote drawing air out.

I vote push just to be difficult, but seriously if you are looking at cooling the water then I would think blowing cool air directly onto the waters surface might be more efficient as opposed to sucking air from random air leaks in the canopy.

blowing fresh air over the water is by far more efficient. The whole point of fans is evaporative cooling. fans pointed at the water will evaporate more water, therefore it will cool better. is this a closed canopy? Is there any reason you can't have one fan drawing fresh air in and directing it at the water, and have another fan drawing hot air out?

The Reef Aquarium Vol 3 recommends blowing air in because sucking air out will likely cause a lot of corrosion on the fan.

I can tell you for sure after I look over a doc at work (brain trust back National hired a Engineer and one of the things they had him studying was having a muffin fan blowing in, or the fan blowing out). Might as well get some of your tax money back.

Personally from looking at the fans I have around the tank/sump, probably better blowing in, rather than having the moist salt air being drawn past the fan. Hey, might be the difference of a fan lasting 5 years rather than 3.

+5 pushing air in, better cooling and fan does not corrode as fast

blowing air across the surface of the water, so pushing I would say

:deadhorse:

(yeah, I went there AGAIN whatigot)

It is a closed canopy. I thought about installing them this way originally, but was unsure if it was the right way to go.

Two fans, one each end. 1 pushing air in the other blowing out. my current canopy is set up this way and both previous custom canopies I have done have also been set up this way, cools the lamps and keeps the heat away from the surface of the water. If you don't have the fans yet I do have a spare 4" variable speed ice cap fan, for you I make to be good deal ya.