Quiet down your grow area by adding a duct muffler to your high output fans. with a near 25% reduction in decibals, you get a great silencer for the noise of any intake or exhaust fan.
GrowAce.com Quick Tip: Adding ducting to any high output fan naturally silences your fan, so don’t think that adding the Duct Muffler will end all your problems of sound. It’s actually a balance of both: too much ducting decreases overall CFM rating and stresses out your fan, but keeps it relatively silent. Too little keeps your max CFM, allows free flow but is extremely loud. Know when to equip yourself with a duct silencer.
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GrowAce

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Sick 360 Segway, man you are The Shit. Great job.
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Helpful and funny
I made mine from a concrete paper form cylinder and egg creat sound proofing foam. 20" long, "8 wide. $18 supplies included. I have a inline fan 700 fpm. %40 noise reduction
Hi there! Can you tell me if this would be helpful for noise traveling from room to room through the ducts? For instance if my husband and I are talking in the family room, our voices carry through the ducts and into our daughter's bedroom.
how does it effect the efficiency?
Too bad your website isn't working. 🙁
Noise reduction is quite significant!
Those videos are in the works. Stay tuned!