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Shhhhh...Quietest 3 and 4 in. hood fans

4046 Views 10 Replies 9 Participants Last post by  WetThumbs
I'm looking for very quiet 3 and 4 in. hood fans to mount 2 in the back of a 125H g tank, just to minimize tank heat if necessary in the summer, as posters here said my Advance ballasts should run cool (one pointed out that his Tek fixture uses Advance ballasts, and the fixture doesn't get above warm to the touch).

Any good models that will plug into outlet (so can be plugged into timer) and good sources for them?
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there are ice cap fans, which are supposed to be very quiet, but fairly expensive (relatively speaking). however a few people just use computer fans, which you can get at any computer parts store. you would need to wire it to 12volt (or whatever is needed) transformer plugs though.
I'm afraid either way, from computer use or aquarium use, you have to pay more for quiet fans. Probably a good idea for me to call some reef supply houses.
Found this very quiet AC power supply fan which looks very promising and the price is not bad at $25: It's not variable speed auto, but it's variable speed manual adjustable at 6 speeds.

There are auto variable speed fans from a marine supply house I believe for only $8-10 more than the above, but I'm waiting on dB noise estimates from the marine supplier which I hope to receive tomorrow.
I've got two Whisper XL fans from

Can't hear them running from inches away - they're QUIET!
silenx is also supposed to be a great quiet fan manufacturer
If I was you, I'd get some Thermal take (Tt) fans off of Their adjustable fans are pretty good, silent and moves a fair amount of air. Just stay away from Rosewill. I have 2 their fans on my canopy, 10x more noise from them than my 8 Tt fans in my computer.
I just added 4 80mm 12volt fans to my 135 hood and I can already notice a big difference in the temp of my canopy (running 4 96watt cf's)

I'm using an old shuttle pc to power them.

Go to they have a rating in decibels for every fan.
I've been buying fans from the guys over at Sidewinder computers for years and currently using a couple of Panaflo High Speed FBA09A12H1BX to cool down my fixture. Since noise is an issue your are looking a anything below 25dBa or lower and the quietest most CFM output you can find is the Scythe SFF21D 33.5 CFM S-FLEX, the only downside to this 120mm (4.75in) fan is the cost of the hole saw to make a nice cutout and the wiring needed (though it's easy). If that's not an issue you won't find anything else out there that can match the 8.7dBA at that CFM rating.

Alternatively you can either use Panaflo Ultra Quiet FBA09A12L1BX instead and use a lower voltage transformer (e.g. 6vdc instead of 12vdc) which reduces the fan's rpm resulting in a lower CFM and much lower dBA.

Keep in mind when using a transformer for these fans it must be DC current and NOT AC. Also, the mA rating of the transformer should be equal or greater than the combined fans amp rating. (e.g. you need 2 Ultra Quiet FBA09A12L1BX then 110mA x 2 = 220mA, therefore a 220mA or higher transformer would be needed for proper operation.
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This is my first post planted tank knowledge is minimal (which is why I'm here to learn), but I have built several computers from the case-up. In my most recent build I stripped out all the stock case fans and replaced with Noctua fans for a noticeable reduction in sound generated by the cooling system. These fans are adjustable in the same regard as the panaflo ultra quiet from the sounds of it. They have some interesting features for computer builds that I'm not sure apply or work with your build, such as optional rubber inserts instead of screws to dampen noise. The color of these fans (tan/brown) is distinct and may not suit your needs, but if they are hidden that shouldn't be an issue and it is definitely worth looking into.

Here's a link to the site I buy my stuff, they may be available elsewhere too:
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