I am building my canopy for my 36G bowfront and i am new to the whole wiring fans thing. Is there a write up somewhere that tells you how to safely wire up computer fans, ect? I am doing T5 lighting so i'll have 2 X 120mm fans as intake/outtake flow and up to 4 X 80mm fans blowing over the bulb ends

Thanks for your time

I'm sure you already have what you need but I bought 2 120mm fans for air hockey tables. They're already 110v so it was simple.

You will need a 12v power supply that has a capacity greater than the combined current draw of the fans used. 1A is usually more than enough for a bunch of fans. They all just wire in parallel (all positive wires tied together, all negative wires tied together).

so buy something like this http://www.12vadapters.com/adapter/power-s...v/1-amp-1a.html , wire them in a parallel, solder the wires and then use that heat shrink tubing to cover the wires. then i should be A-ok, right?

Perfect.

Just a suggestion but I would have both fans blowing in rather than one in and one out. With both in you get the full CFM of both fans. With one in one out the second fan only moves the air the first one feeds it so does not contribute anything thus equals only one fans CFM.
I use both blowing in, one in each end on a 100G with a completely enclosed canopy except the fan in each end and equal sized holes in the roof of the canopy over the reflectors. This takes advantage of convection too even when the fans are off and works quite well. I also use a DC variable voltage power supply so I can vary the fan speed according to cooling needs and fan noise.
I sold my 1/4HP chiller and use fans alone today with 2x250w MH and 2x140w VHO and stay 79-81 year round using only fans, and an auto topoff that is.

from my experience it doesnt take much to cool down a tank. i was hitting 86F in the summer. so added a 70mm fan at 6v and it brought it down to 79.

i think if its too much then your heater would work harder/on all the time.
and evap becomes a problem. try to find your sweet spot. add a fan speed controller.

Thats the purpose of the DC variable voltage power supply I mentioned above. They are about $10 or less at WalMart, Frys Electronics and I got mine at Harbor Freight Tools for $5.

Or you can buy a fan with the speed switch built in and wire it up how the others are saying

alright i looked on newegg for fans. these look like they move alot of air but are they going to be obnoxiously loud (45.9 dba, but moved Air Flow 133.60 CFM). I want a good fan that will move plenty of air but not really loud. any particular favorites?

Thats a lot of air flow. How big of a canopy are you cooling? My canopy is 18"x60"x16"high so equates to about 10 cubic feet of volume. My two fans are 120mm (4") Vantec Stealths that move 53 CFM each at only 28 dBA. With both blowing in and equal sized exit holes in top that gives me over 10 complete air changes per minute (106 CFM) which allowed me to sell my 1/4HP chiller.
http://www.newegg.com/Product/Product.aspx...N82E16811999614
The Scythe fans here are supposed to be even quieter:
http://www.newegg.com/Product/Product.aspx...N82E16835185005

dBA ratings are deceiving, going up one dBA can be quite drastic, its like a factor of 10 or something not just one time louder so 45.9 dBA would be like a hurricane. Find the largest size lowest speed fan you can, they are usually the quietest.

Heya,
It's a 36g bowfront, so i believe the back is 31" and the widest point of the tank is 16". The height of the canopy will be around 13," so i guess the cubic footage is 3.75. I didn't realize CFM meant "cubic feet per minute." So i guess the fan i picked out is overkill then. Although i do have the icecap ballast which will over power the lights, so i just want to make sure i get a good enough fan that will cool the lights but not be obnoxious

I have 2x250w MH and 2x140w VHO actinics in a completely enclosed canopy and the two Vantecs cool it no problem, even in summer months.

Key things I figured out were if using a single fan, try to have it down low and blowing across the length if possible. If it is in back again keep the fan low, blowing in and have the exit hole up high on the opposite end so you evacuate as much air as possible without short circuiting. The old one fan in and one fan out method is a waste of a fan since the second fan only moves the same air the first one feeds it and does not contribute or add to the flow, plus fans pushing out get really gummed up with crud from the moist air and salt spray.
It good you use a variable voltage DC power supply as you may not need as much cooling in winter months plus slowing the fans down quiets them even more. I often run at 10.5v or even 9v in winter then back up to 12v in summer. They are cheap and can be found places like Wal Mart in the electronics section Frys or New Egg for less than $10.

Every 3dB increase is roughly a doubling of noise; 43dBA is twice as load as 40dBA, 49 dBA is eight times as loud as 40....

If two fans move the same amount of air, the one with a larger diameter and lower speed will make less noise. I like Papst fans but the Vantecs AZDesertRat uses at 28dBA will be very, very quiet for the flow rate.

Not to hijack but I'm interested in doing the same thing... AZ, do you mind linking up an example of the variable voltage power supply? All I"m finding is ones that are hundreds of dollars.

The one next to the bottom of the page here for $9.99 is a good example. Notice it has a slider switch which changes different voltages from like 3v to 12v DC.
http://www.voltage-converter-transformers....-dc-supply.html

I got several of them at Harbor Freight Tools years ago and they are still working like new but last time I checked they did not carry them anymore. I have seen them in Wal Mart by the cameras and phone chargers for about $10-$14. You just cut the DC pin plug off and wire the two wires to the red and black on the fans. One power supply will usually run 3 or 4 fans depending on the fans watt ratings.
Frys Electronics has lots of different ones in the store but not much on their website. i found I had a few around the house already from old DC appliances I had thrown away, really anything 9 to 15v DC will work but the variable voltage is better so you can adjust fan speed.

Gurnie, as it sounds like you haven't done much electrical, I'd like to warn you to the obvious. I probably don't need to, but you never know.

Put the heat shrink tubing over the wires before you solder them together. Then slide it over the the solder joint and shrink it.

It shouldn't need to be said, but you would be shocked at how many people, even experienced people will forget to put the tubing on it first.

at first i read this and i was like "huh?" But then i laughed. Yeah it would be pretty friggen hard to get the heat shrink around the soldered wires without splicing through the heat shrink. Your comment made for a good laugh.



So back to fans.

Is it really worthless to have two large 120mm fans? my set-up was going to have 6 fans, 4 50mm blowing across the bulb ends and one 120mm as an intake, one 120mm as an out take. My bulbs will be over driven by the icecap ballast, so a little extra air circulation couldn't hurt

Personally I think thats way overkill. If you have the room I would install either a single 120mm fan in one end blowing across the length with an equal sized exit hole on the opposite side. Or an alternative would be a single smaller fan, like an 80mm in each end, both blowing in with exit holes in the roof of the canopy above the reflectors so hot air rises but light does not hit the ceiling. This is basically mysetup but with 120mm fans.
One thing I have found is smaller fans are usually louder since they have to turn at higher RPMs to move the same amount of air as a larger fan. 120mm might look big in a 36G canopy though.

Big is good. Along with them being more quiet, they also blow over a larger area. While two would do it just fine to keep hood temps down, an extra pair for the T5s wouldn't be a bad idea. With bulb temp being more critical with overdriven T5s than MH, any added airflow you can get will be a benefit.

So four 50mm and two 120mm sound good to you?

Nah. I'd do 4 120mm. Two for ventilating the hood and one on each end of the T5s. Remember, bigger is quieter. Those 50mm fans could be noisy.

Oh so two on the inside of the hood and the other two working as an intake - outtake

Intake outtake is a waste of fans. Come on, you have maybe 3 cubic feet of space to cool, 2 fans at 53 CFM each gives you 106 CFM or 35 complete air changes a minute, way more than sufficient. The bulbs are not that long so a fan in each end placed down low will more than cool the bulbs plus evacuate the canopy if you place exit holes up high. I do 3 times the cubic feet of space with the same two fans and 780 watts of MH and VHO light in it. Overdriven or not 35 air changes is a lot or air, you will probably end up slowing the fans down as evaporation will bea killer at that rate. My tank never goes over 81 degrees winter or summer with that configuration and no chiller.

It amazes me how much cooling I get by convection alone when the fans are not on. I can place my hand over the holes on top and feel a nice breeze by convection alone. Proper exit hole placement is critical.

When wiring these in parallel, I assume that all of the positive wires (say, 3 fans) are soldered into the single positive of the power supply, and vice versa. So 3 wires soldered to one and then heatshrinked. Right?

I gotta rig up some fans for my LED array and might toss in another couple just for air movement.

Yes. If you daisy chain them it cuts the speed in half every time you add an additional fan. Take all the leads back to the power supply individually for full speed and full voltage.

So daisy-chain = run them in series (ie, don't do that). Got it.