Fan circulation? 2 in && 2 out || 4 in

[surg_xero]

My question is one that pertains to whether fans sucking air out of your canopy can be beneficial. What would circulate air better 2 fans blowing air in from the side of the canopy and 2 fans sucking air out mounted on the top of the canopy and opposite from the other 2 OR 4 fans blowing air in from the side of the canopy with passive exit holes on the top of the canopy and opposite from the 4 blowing in. Has anyone personally tried both these conditions?

Thanks,
Steve

[xtrstangx]

IME, its always worked better for me to blow cool air in.. the hot air will find its way out.

[Arik]

If your canopy is really tight, then the 2 x 2 is a good idea. If you have adequate ventilation out the top, the 4 blowing in would be ideal since you could aim them at your heat sources and water surface, and fans blowing in theory should last longer since they are less likely to drawn in water/salt.

[silverwolf72]

Blowing in has the advantage in that it is more directional while sucking out is more diffused so the air is comeing from all sides and you won't really get the heat away from where you want it. Main reason you see fans pointing out on things like computers is to keep from blowing dirt into it at a minimum.

[kgross]

The other advantage of all the fans blowing in, is that you get more air movement throught he hood (as long as there is areas for the hot air to get out of the hood), if all of your fans are 500 cfm, with 2 in and 2 out, you are only moving 1000 cfm of air, with all 4 blowing in , you have 2000 cfm of air movement in your hood. Plus you are not moving the hot moist air through your fan, which will cause your fan to fail quicker.

Kim

[84scrambler]

I personaly went with a cross flow. One fan on the left and one fan on the right. One of the fans blows in the other blows out. To me this seems like the most efficent way of moving air. I have a 180gallon tank and when it hits the upper 90's my tank doesnt go over 84 degree's. I am also going through about 5gallons of water every 3 days.
I would be more concerned about the passive approach as you are relying mostly on a pressure variance to cause the heat to rise out of the holes. If you were to put the fans on top then you forcefully remove the air generating more cross flow over the water surface.