fan advice

Hi there,
I'm using a very small space (1m cubed) with a 400w hps. The light sits on top of the growspace so some of the heat is lost that way



Ive just about managed to keep temps down by taking the sheet covering the entrance off. Unfortunately smell is an issue though so i've decided to get a cheep as possible carbon filter which would mean having to create a closed environment and get an extractor fan to deal with the temps.
So I was thinking of getting a 4" bathroom extractor and cutting a hole in the top of the grow space(underneath turntable in the pic). DWill that surfice for my metre cubed area? bare in mind that some of the heat is lost from the light being outside the grow room.
I will put the carbon filter on the extractor, should i use ducting or can i just connect it straight to the fan?
if anyone can help thatd be great as this is not my strong area
cheers

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Nice vertical shed - kind of like a bookshelf. Only $99. I am about to buy this one and use it for an aerogarden unit. I won't need all of the height necessarily, but you never know!

em i would use about 3ft ducting maybe more depending on the speed of ur fan it may pull to much out there4 it misses filtering through the filter so add ducting.