I am using a freezer as a growbox. I have installed a 120mm 205CFM case fan to exhaust the hot air. The exhausing part works but that fan puts out some serious noise when blowing air out. How can i lower the sound of the exhaust? Right now you can hear it thru the garage wall. This is the last obstacle for me to start my very first grow. thanks!
I would try ambient noise. Pick up a couple of cheap water pumps at the home store and a tub, (maybe 25 galons,) put pumps in tub, plug in and listen to flowing water.)
Increase the fan size by 30% and add a variable speed control to the fan. Run the fan at a low speed. With the increased fan size you will move the same amount of air with less noise from the fan. Also reduce bends in duct work.