Wish I read this earlier I just made this mistake but am using a 6 inch inline 240 cfm the temps went up from 78 to 86 and the filter pad hardly does anything for the odor. I only have two plants in 4th week of flower stage. I wish I could by a professional scrubber but my cab is only 3 x 3 ft high
I have a 2x2x2 cab and ended up making a diy carbon filter. It works well with this pc fan, and i have it blowing through the filter. Granted I haven't flowered yet but no smell about a month into vegging which is pretty potent without the filter. It really just sounds like a computer running, virtually silent with the tv on. But that is with it mounted inside the cab, blowing into a filter mounted right above it on the outside. Not exactly stealth... I have it under volted to 9v with a radioshack adjustable transformer. It's discontinued so it was tough to find but I found one through avayagroup I believe. If the DIY filter gives me any doubts going into flowering I'll probably go for a Can-Filter 705. Pretty sure you can grab one of those for 40 bucks with a pre-filter online. It's only a foot long and four inches round which is perfect for a micro cab, wish I knew about it before building one... I spent about 40 on materials and mine's six inches round, about a foot long.