Per ventilation, you need to pull the air away from you and over the processor, then out, with the makeup air coming from behind. Hypothetical CFM is offset by outside humidity, air friction due to bends of corrugation in the ducting, etc. I have a very nice 20" roller transport machine, but have never even plugged it in, though I have seen it in use prior to my ownership. Would like to get rid of it to save
space. I prefer to use drums, but not Jobo. They fill and drain way too slow for me.