Great idea! I’ve not used nets in YEARS for many reasons so I didn’t even think about this one 
lol that may have been me. 
In my defence, I have 2x 6" running for a 4x4, and all my tents run 6" not 4" except for my upstairs breeders which have a canfan and that thing’s scary strong.
I wasn’t sure if I saw it on here or Reddit so it probably was if you’ve done that 
This is what i use. I also wish i could go a little slower with the fan. After reading everything here i had no idea the speed controllers can be harmful for the fan motor.
I see some have a “var” switch, i have no idea what that is. Hopefully this doesnt burn out my fan but it has been working good for a few weeks everyday all day
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I would just get the speed control Vortex recommends. I’ve only bought Vortex for extractor fans, as they are so powerful, for the last 24 years now.
The correct speed control, does not harm your fan motor at all, I’ve recently replaced a Vortex that ran 24/7 for 16-17 years.
I’ve also plumbed a 6" to extract 4 tents, into a single CAN filter, every tent side was sucking inward, once all were zipped up.
Some cheapo fan may shit the bed from a controller, but a real Vortex, I do not think so, no way!
So I dug into the technical question a bit and this particular Vortex uses a PSC motor:
Still digesting this really good and succinct white paper for HVAC engineers about methods of speed control and AC fan motors:
Speed-Control-for-Fractional-Horsepower-Motors-FE-1000.pdf (192.5 KB)
@FieldEffect @Nitt this is your kinda shit I just know it
@Dirt_Wizard It is I’ve been refraining from commenting because I don’t have experience with those blowers or inexpensive controllers.
Typically you’d do this with a VFD but that’s usually only worth it for big (>1hp) motors. Variac would work, but probably looking at $50-$100 for one of those. Most of the motor speed controllers (not the same as a dimmer) will use a U2008 controller that does something called phase control to drive the motor with a triac. I think it will be unlikely to find something inexpensive that is well-filtered enough to avoid an audible noise. The Vortex-branded solution is what I would buy, they purport a “high-gain RFI suppression filter” which is a little technically incorrect but almost certainly aimed at taming that issue.
Edit: The “Vari-Speed” is only $30 even from Grainger I think it’s a no-brainer to get that. There is a minimum speed associated with all of these sort of controllers it may not get you a lower overall speed than what you are getting right now
Very interesting thread….
I am out of likes for awhile .
What you are describing is how we use to do it back in the wildwest days. I never had an issue with any of mine , but I did know someone who had a fire start because of their spliced in dimmer switch.
I do not recommend it doing it nowadays , especially as I have never had a fan be still moving too fast with it turned all the way down. In that case I would recommend a smaller, less volume fan.
Yeah, I’m an old school grower. I just remember these being the one to get back when I started, and I got it for the same price as a 6" AC Infinity blower, so it was well worth it!
I found the one everyone seems to be recommending for under $15 on Amazon. Waiting for delivery now. Thanks guys!!
https://a.co/d/abq80yd
you have any specific brand to recomend? or whats this style called since people have mentioned a few different styles on this thread. im just looking for the most basic option that isnt sketchy and a fire/electrical hazard 
Eventually ill get a 6 inch AC infinity cloudline for my flower tent and swap out this beast of a 4 inch vortex fan for the one currently in the flower tent, but not looking to drop that money quite yet after squeezing for a new-to-me used tent/fan/light
But also if a controller is $40 i question is it worth it, or should i just spend a bit more for the new fan…
Ohhhhh the dilemmas of where to spend money on our grows never end, do they? haha
Edit : clicked the link above after typing this comment and it looks like the one you linked, or good enough!
Absolutely not 
Or this 
Yeah, I’m a cheap bastard. If I can build it for 19cents, watch me save 134$ lol
Search for a potentiometer. Light dimmers are not the same. They do make wall outlets with a built in potentiometer for commercial applications, like restaurants, etc. A residential style exists, but seems less common.
For your money, the one I linked a couple posts above will do the job nicely for Vortex fans.
not sure about this but personally i wouldn’t mess with wiring any of my own stuff because thats not my wheelhouse. were talking about fans that already have a variable speed controller but on low is still too high of a setting for our needs, so im not sure how a dimmer would work into that but the $15 controller someone posted an amazon link to looks like (and sounds like from @Pigeonman) itll do the job
I looked at doing this once and tried a purchased speed controller from a grow shop. The reason I wanted to slow the fan was because it was too loud on full, turns out it is just as loud with the controller, just a different type of sound so I took it back and bought a new multispeed fan of a bigger diameter and turned it on the lower settings. All I hear now is the air rushing out the vent 
I thought of making something up to try but decided to use tried and tested gear since growing is not exactly legal here and I don’t want a fire or anything 
Using a standard dial dimmer from Home Depot should work, just make sure it can handle the fan’s power.
You can find these type controllers on discount as I hear ya on the full price B.S. 
If you.have access to marketplace or kijiji, you can do what I did and set an alert for cloudlines. I bought 2 at about 1/3 of the retail price from folks that gave up growing after 1 cycle.
“I thought I wanted to grow pot but it’s too much work.” was the usual line.
I got similar kit from folks getting out of data mining things like bitcoin.
Damn I meant to buy one weeks ago and how this model is gone from Amazon! 
