i vent my 400w hps straight into my wall, no tubing to travel, heat is dispersed immediately, i honestly never filled my scrubber with carbon so ive been doing this for well over a year with no problems. Humidity is already 85% around here so im not worried about what i pump into the walls. I actually had 2 cops stop by to pass out fire safety pamphlets cause there was a fire in the neighborhood, in full bloom, no problems. (although it was scary to realize how easily i could have been busted right then.)