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Help - Built a new canopy - looking for cooling fans now

1120 Views 12 Replies 7 Participants Last post by  KlintZquarium
I just built a new canopy for my 55gal. Its made out of 3/4" thick pine and I'd like to install some cooling fans into the canopy. I have about 2" of room right above the rim of the tank where i could install a few fans. 2" gives me somewhere between a 40mm - 50mm computer fan that would fit. 50mm would be kind of tight but i could make it work. Ive been searching the web and can't seem to find one that has a single flange and would flush mount directly onto my 3/4" pine. All the fans I see are the "block" type with flanges on both sides and I don't see how this could work. Can someone point me to the type of fan i should be looking for? Ive never dealt with computer fans, so I'm kind of lost when it comes to the terminology. Do the "block" types separate and attach by sandwiching the piece of wood? Im lost.

Please help.

Something like this (link below) would be ideal but they don't make anything smaller than 80mm.

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The fan "block" does not separate. As you can see, that fan you linked is actually a "block" type fan that's simply attached to a mounting bracket. Typically when these fans are mounted in a computer case, there's either a mounting bracket of some type or else a grill something like this that can be used essentially as a washer for bolting the fan on (Grill->hole in case->fan block all bolted together).

Most 50mm fans are only 10mm thick, so one possibility would be to take a router and cut a square the size of the fan housing (but not all the way through the wood) and then cut out the 50mm circle in the centre. you could then bolt the fan onto the remaining corners. Another option would be simply to build some type of mounting bracket.
When mounting the fans would it be best to have them both blowing out of the canopy? Into the canopy? Or one in, one out? They will be located between the surface of the water and the bottom of my light. There is also a full length 45" x 3" cutout across the whole back of the canopy so "suction", for lack of a better term, will not be an issue.
i have never used fans before, but i would guess that you want one in one out, to create a flow of air...if they both point out there would be a negative pressure inside, so air would have to leak in, vice versa with both pointing in
I would want the fans mounted on the back, out of sight. Is there not room there? With the opening on the back there will be no problems with airflow. The full size of the fan doesn't have to be open. Can you put two strips of wood on the back opening to mount the fan. No problem with it being in the middle or side. The air you blow in or out will be replaced by air going the other way, regardless of where the fan is mounted. Assuming you have water circulation, any cooling will be spread over all parts of the tank. For me, I would want to pull air out off the tank rather than blow air down onto the water. Amount of air moved won't be much different but I would not want to have the air blowing directly on the water to upset any fish. They likely would adapt quickly but just my thoughts.
If you go look on ebay or google there are some nice computer fans that are sealed/waterproof and ballbarring for like $10 or so, not bad for humid areas you can also go look at a hydroponic shop for the sealed versions but there a bit more close to $30 but should come already hardwired with plug if thats not your area of expertise. there is even a demo of a guy putting in under water to show how well it is.

depending on if your just trying to have the fans blow over the top of the water to cool the tank or to keep the lights cooler kinda depends on how id run them, id prob have them pull the air out and face the back or top depending on your layout/build.
If your purpose is to cool the tank water by evaporating some of it, then it will work best by having the fans, both of them, blow in across the water. That gives the maximum air velocity across the water. (the opening in the back of the hood lets the air out.) But, if you are trying to cool the light fixture or fixtures, they would work better blowing out, so the whole light fixture would have moving air across it, not just a blast of air at one spot. And, the fans would be in the ends of the hood - actually that's where I think they should be anyway. I haven't done any testing to support this, but it is how I would do it and why.
Thanks for the input. Maybe Ill do 2 sets of fans. If I mount 2 on the upper portion in the back of the canopy that should take some of the heat off of the fixture. Then have 2 side mounted fans on the lower portion to blow across water, not directly onto it. That should help with the water temp as well.

I see a lot of fans have a decibel specification. The fans Ive been looking at are between 10db and 30db. Does anyone know if this is even audible? And if so, how loud is this? Is there anything i can listen to to get a better idea of what 30db sounds like?
I would guess the fan on your computer would be somewhere near that. Sometimes it is not the actual level of the noise that bothers me as much as the constant noise. I would not want four fans all running full time. If I understand your plan, will not the same fan which cools the ballast also be taking heat off the top of the water and out from under the canopy? It doesn't really need to be a full rush of air over the water. Just enough to carry the moist air out and then more water will evaporate into the replaced air.
Are you considering adding a small button type thermostat to turn the fan down at night when the lights are off? I would want that or the fans tied into the lighting so that the fans were not running while I am sleeping.
Noise is my biggest concern as my tank is in my living room/dining room/kitchen area. Its pretty much one big room where we spend most of our time. This is why having fans on the back worries me. Being that the tank/canopy is about 1" off the wall, i feel that the sound will be deflected off the wall and slightly enhanced. And, being that it is so close to the wall, I worry about hearing the air hit the wall as well. I would only run the fans when the lights are on. I would love to tie it into the fixture somehow but I'm not really confident in my electrical skills and would hate to mess up my new fixture. They will most likely be on the same timer as my lights this way I don't have to worry about wiring anything together.
Electricity and water do not mix

there are some nice computer fans that are sealed/waterproof
Sealed and waterproof are your two biggest concerns. Find a size relative to what you need with the desired airflow. Then modify your holes as necessary.

Popping air bubbles and humidity means any standard computer fan you use will not last very long.

Fans used around hydroponic equipment should meet the specs you need.
Noise is my biggest concern
The sounds of flowing water may or may not drown out the hum of the fans. Go for the lowest decibels you can get for the required airflow.

Decibels are directly related to fan speed and the shape of the blades and housing. A quiet-rated fan can turn out to produce lots of noise just by the shape of the column of air flowing through the equipment. [To demonstrate, just blow over the top of a bottle--the sound changes depending on the air column inside the bottle/level of liquid.]
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