@fettled6 , in regards to your carbon filter, how do you have that set up? Meaning, where is the fan in relation to the whole setup? I used to have problems with smell sneaking out too, until I connected my
fan directly to the carbon filter. That way, the fan is pulling air directly from the filter without any chance for sucking in unfiltered air through small holes in the duct or cracks in the light hood. That way, it's positive pressure through the rest of the system, so no chance of dirty air getting mixed in. Sounds simple, but makes a world of difference.