Recommend a very quiet fan/carbon scrubber

Larger fan running at a lower speed and a larger carbon filter. I'd just build the carbon filter if you can.
The fan/filter combo will totally depend on the size of your grow. How big of a space are you venting?

 

Checked your blog, you've already made a carbon scrubber?
Sounds like you just need a fan and some ducting for it maybe. You only need about 35cfm to keep things well ventilated so a crossflow fan pushing twice that cfm or a bit more would work well.

For stealth I'd recommend the S&P TD-100 4" fan. Quietest inline fans AFAIK. It's WAY overkill for your setup (140cfm) and would need a fan controller to tone down the airflow.

I looked into crossflow "squirrel cage" fans and haven't found anything with a 4" opening. You could always rig something to reduce/increase the ducting size though.

 

I was going to post recommending the S&P TD 100X 4" I have 2 of those and 1 TD-150 and love them the 150 is a little loud (whooshing air, not motor, I have it on high) cheers to Inphu and Robotic for great suggestions +rep around!

 

Viola!

 

Nice I will have to get me a couple of those.

 

That sure looks a lot like
- Harbor Freight Tools - Quality Tools at the Lowest Prices

 

Those fan speed controllers will still generate some humming. In fact it's about the same as a light controller from home depot. If your in Europe I would buy a Ruck Iso...the quietest fan you can find. But in the US i'd go with a 4 or 6 inch centrifugal fan turned down real low. Also I would build a small box to house the fan and insulate it with either Dynamat or something similar. Automobile road noise deadening stuff.

Vortex fans are quieter but they lie about their CFM ability. The real reason they are quieter is because they don't move as much air

 

After doing some more research last night I found that Grow2 is right. Especially in the case of the S&P fans, they do NOT like to be controlled. S&P fans have a "low" and "high" setting although I see little difference between them. I believe the "low" setting for the 4" S&P fan is 100cfm which is prolly overkill but maybe you can work out some extra ducting or something to kill the airflow a tad.

Also another thing I forgot to mention is the ducting itself. I dunno how you're planning on running ducting but you can buy insulated 4" ducting which will definitely quiet down the airflow noise. If you vent into the filter, the filter will act as a bit of a muffler as well.

 

When I was Wiring the S&P fan it had instructions (wired differently) to the controller. I think its better to have a controller that is hard wired to the S&P.

 

that is good shit. im bout to make this lol

 

Cool hope it works for you.

 

Wow, your space is so similar to mine, except mine is a broom closet. The big advantage yours has over mine is the movable shelf, which allows you to better cool your lights. Right now I have 128W of CFL and the temps are about 81 - 85. I have one 88 cfm, 120mm exhaust fan in the ceiling of the cabinet, (about 3 feet above the lights), one 40 cfm intake fan at about soil level, and a passive hole thru which the cables feed. I installed the intake fan mainly to blow on the leaves, but it does push air to the other side of the closet so it's helping to cool also. But all this is not enough because I want more light. I was planning to add another 90 cfm exhaust fan in the ceiling, and make another intake hole near the lights. I have my lights in power strips mounted on boards, so they are movable, but the board/powerstrip combo takes up valuable space! You can see my set-up on this thread, (where fidelity suggested the additional exhaust fan). Post # 6:
http://forum.grasscity.com/general-indoor-growing/582973-2-27-watt-5000k.html#post7228817

Anyway, another problem with my set-up is the size of the exhaust fan (120mm or 4.75 inches), which makes it tricky to fit a filter on it. And even trickier with 2 fans. If you have figured something out I'd really like to hear about it. My plant started stinking as soon as I put it in the cabinet and turned the fan on (it was probably about 5 weeks old, but not flowering yet). It didn't smell like MJ or skunk, it was sort of like the smell of tomato plant leaves. I put a carbon-impregnated pre-filter on the exhaust fan, which worked for a while, but it really slowed the air flow. So I made a carbon filter from a colander, which you can see on the other thread. It's working for now, but I don't recommend it.

Based on the info here (thank you, all!), I think I'm going to invest in the S&P fan and make one of the pencil cup filters. I don't have any room for ducting, so I guess I'll just tape it to the fan.

How's your grow going? I hope your plants don't smell as bad as mine does. Mine is just bagseed so I have no idea what it is.

 

Bhobo, I didn't click on your Staples link before. The large pencil cup (4.75" diameter) is exactly the size of my exhaust outlet! I could tape the filter to the hole, and run a straight line of flex. 6" ducting down to the reflector. (I have plenty of room for a straight line of ducting, just no room for turns.) Then make another filter for the other fan. Or maybe I won't even need another fan if I can cool the lights better with the ducting!

 

I might just go with 4" ducting or 5" if you have space problems 6" gets pretty big. Also if the space is short just get a piece of solid ducting they come in different lengths or can be cut. then its a nice rigid duct with minimal resistance (the wire accordion shape gives some air resistance)

I don't have a movable shelf btw I move the lights up and down. You can make a 6" filter with some chicken wire type stuff. Look in my DIY post at the bottom and I have like 5-6 links of slightly different style filters to fit different needs.