Advice on cooling fans in canopy

D

doowain9999

New member
I'm currently building a canopy for my 72 gallon bowfront. It will house 2X175W MH, 2X65W 10K, and 2X55W actinic. I've made it 14" tall, so the MHs will probably sit 13" from the surface of the water. How many and what size fans would you install in the canopy?

I've seen that most people go with the Radio Shack fans. They have 3" and 4" fans. I went to the local RS today and checked them out. I know it's only an inch, but by looking at them, it makes a pretty noticable difference.

Thanks.
 
I use 2 120 MM (about 4") fans in my 6ft canopy. You could probly get away with one of those since they are only 175 watt MH or 2 smaller 80 mm.

I buy mine off ebay theres always people selling 120 mm fans that move 93 cfm thats pretty good flow and they arnt that loud. Way more quite than some iv had and they are only about 6 bucks with shipping.
 
I use PC fans, one blowing in, one blowing out. They lowered the tank temp to the point that the heater cuts on. There are 3 175 watt MH in the canopy and 2 five foot VHO bulbs.
 
I hate to disagree with Alarmguy, but I think that having them both blow in will be better for the fans! Having one blow out will allow for salt spray to get inside that fan causing it to fail sooner than you want it to. If you have them all blowing in, the salt has a harder time getting inside the fans b/c they are blowing the air away from it, and pulling it in from the outside. Just leave the back open, and have all the air go out the back! HTH
 
I have a 120mm Vantec Stealth fan in each end blowing in with 4" exit holes in the very top of the completely enclosed canopy. By having holes on top you also take advantage of convection when the fans are not running. With one in and one out you only have the CFM volume of 1 fan, with both blowing in you move twice as much air.
 
I think having an open canopy back (or partially open) OR vent holes in the top with both fans blowing in is the best route for a number of reasons.

First is the forementioned salt creep. These fans were not designed for a moist environment and WILL fail after a while.

Next is with both blowing in, you have twice the air movement rather than one in and one out. Example say you have two 100cfm fans. With one in and one out, you are moving 100 cfm through your canopy. With both in, you are moving 200 cfm in your canopy. That air has to go somewhere, thus the open back and/or vent holes.

Finally, with one in and one out, you will develop an airflow pattern that goes from one fan to the other and will have dead air space that does nothing but heat up. Not an efficient way to do things.

That is my $0.02 worth
 
at walmart they have clip on fans thier like 7 bucks and they even oscelate i use one of those and they put out alot of air as well as quiet.

you can clean them after a year or so or just dump it. and buy a new one
 
I also use a pair of 120mm fans in my 6ft hood which houses a 2 actinic VHOs and 2 250 MH array. I have both fans blowing in and wired them to a self built thermal fan speed controller. I found this to be a rather nice design as the fans only blow full force when the hood temp gets too high. The variability also reduces fan noise as they are not usually blowing full force. If you get the chance to integrate the fans into your hood, I am sure that you will be much happier than having something clipped off to the side or something that you need to replace every now and then.

:fish1::hammer:
 
I got mine at a local electronics store. If you have alot of choices, go by the scfm the fan moves but also consider the decibals. Most have both numbers on the packaging.
 
AZ - looks good but doesn't seem to move allot of air. I've been looking at 130 cfm (as oposed to 53 for vantec) that rates at 48 db. Is there a big difference betwen 28 and 48 db? I want the air flow I need that is still reasonably quiet. Thanks
 
That's the trade-off. The more air, the louder it is. Yes, there is a noticable difference between 28db and 48db. The question is, do you want to be pushing that much air all the time, or just when you need to?

:fish1::hammer:
 
I will have my fans hooked up to an ACjr. The fans will only come on when a certain preset temp is reached. I'm very open to suggestions and recommendations. Thanks all.
 
Not knowing that particular device, does it kick on the fans to full, or does it do variable speed control for them.. From experience, I have found it rather annoying to be sitting around and then having the full fan noise kick in for a few minutes, then turn off once the temp drops below the setpoint. If you are going to be blowing a large volume of air, you will most likely notice the fan noise if it is just an on / off device.

:fish1::hammer:
 
AquaController Junior is not variable speed, it's on and off at preset temps. That's a good point about on and off for a few minutes, it could be annoying. But I need to balance that with cooling my tank, so I'm not sure which direction to go in.
 
Chances are, depending on where the sensor probe is, once that area cools off anough, the fans will kick off, then it will just heat back up. The key to a device like this is to place the sensor in an area that will not have dramatic temperature changes. I strongly receommend a variable thermal sensor if you have the abilities to acquire one or make one. A while back I used the following thread: http://www.reefcentral.com/forums/showthread.php?s=&threadid=644033 to make the setup I currently have. I am running 3 120mm fans (2 in hood, 1 in stand) with 2 thermal sensors to control the two different zones I have them in. Aside from really hot days, the fans themselves purr quietly along and the tank temp stays rather stable.

:fish1::hammer:
 
The ACjr turns the fans on or off depending on tank temp, not air temp. So I think if the fans are kicking on and off on a 200 gallon system I would have much bigger problems than noisy fans. Don't you think?
 
Ahhhhh... ok.. that does change things a bit. Most DIY temp things that I run across are built from PC components, and thus not placed in the water, so I was basing it on the assumption that it would be measuring the hood air temp, not the water temp. But, yah.. You would have yourself some really effective fans if they could cool off your tank that fast. =)

:fish1::hammer:
 
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