Where to put fans?

[captain639]

Where should I locate fans in my canopy to get the best air movement. Right now I have 2 fans in the back of the canopy, one blows air into the canopy and the other blows it out of the canopy. They are both on the back side.

Should I maybe make them both blow air in, or both blow out?

I also want to add 2 more fans to help with the air flow because 2 just isn't enough. Where should they go and which direction.

Background:
150g tank
6 x T5's with individual reflectors
Canopy is enclosed on all sides

[SWaddict]

I would put them in the ends, one blowing in and on blowing out. Or you could have them both blowing in, forcing cool air over your lights and out the back... Either way I would add them on the ends.

[seascapes.az]

Originally Posted by SWaddict

I would put them in the ends, one blowing in and on blowing out. Or you could have them both blowing in, forcing cool air over your lights and out the back... Either way I would add them on the ends.

+1

[OAL-T1V0M]

if you can get away with it, 2 in on the sides or back, and 2 out on the top of the canopy... just my three cents..

[AZDesertRat]

I have experimented with canopys and fan placement for over 20 years now and have found by far the best option is two fans, one in each end, both blowing in and with equal sized or larger exit holes in the ceiling of the canopy.
I constructed my present canopy 6.5 years ago with this configuration and it has allowed me to sell my 1/4HP chiller and cool ly 100G, 2x250w MH and 2x140w VHO, with fans only here in Phoenix. I use two Vantec Stealth 120mm or 4" computer fans that are extremely quiet and affordable at $11 to $14 apiece. They are powered by a variable voltage DC power supply which can be found at WalMart for about $8-$10 so I can vary the fan speed with the seasons when I need more or less cooling. The tank stays 78-80 year round with no other cooling except fans, the house has a digital setback thermostat so its warm during the day when we are at work and is always a little warm to save energy, we use ceiling fans a lot.

I have tried AC fans but you can't vary the speed and they are noisy. Larger fans, smaller fans, more fans, less fans, one blowing in one blowing out, one on top, both on top, both in back with one in and one out, both in back with both blowing in and holes on top, and any thing I could dream up and none compares to what I described. Two fans both blowing in gives you the CFM volume of two fans, one fan blowing in and one out is inefficient in that you only get the volume of one fan, the second only moves the air the first one feeds it. Fans on the ends blow across the ength of the water surface for best water to air exposure. Holes in the top take advantage of natural convection, you would be amazed at the air flow I get even with no fans running just from heat rising out the top and cooler dry air drawing in the sides to replace it. Fans blowing out are bad news since they pick up moist hot air and fail pretty quickly in comparison.

I spent many hours researching and testing all this and it paid off handsomley, no chiller and no higher electric bills. The only drawback is evaporation but I took care of that with a Spectrapure UPLC-II top off device which iis much cheaper to run than a chiller! I'd be glad to show anyone interested my canopy and fans if they drop by.

In the hottest part of summer I stick a WalMart clamp on fan over the sump and stick it on a timer so it runs when the halides are on too. If I leave it on all the time it cools the tank too much and the heater comes on plus evaporation goes way up unnecessarily.



Clip on over the sump:




The canopy is completely enclosed on all sides and top:


Corals do well as you can see:


A small amount of light can be seen directly from the ends but its not much as the mogul sockets block most of it. No light goes out the top holes as the reflectors are between the lights and exit holes with the false panel I mounted the lights on suspende below the canopy roof for a dead air space.
The canopy is about 16" tall overall and opens on top with piano hinges plus has two doors in front for feeding.