Will this grow room work?

Okay. I plan on making a 3.5ft x 3.5ft x 6ft growbox pretty much with a 400watt hps inside it. I'm going to be growing with Co2 so I don't really need to much ventilation. I already checked the temperatures the room will get and they stay between 80-90 with my fan on. I do plan on adding ventilation though. Im going to vent the heat out a hole in the side and into a small airtight box outside the grow box. Ontop of the small box that the warm air is going to, Im going to install two of these homemade carbon scrubbers to filter the smell and along with other chemicals.

The filter looks like this.

All in all, this should work pretty well right? Also, do I need to vent the Co2 out of my grow box?

did you say you were only growing 2 plants?.
have you started to grow yet.
how long do you plan to vegg for?.

here is my 2 foot by 2 foot by 6 foot homade cab,,might help give you some ideas,,,good luck man https://www.rollitup.org/do-yourself/49801-homemade-cool-tube-cab.html hope this helps a bit

Keep on Growin

HoLE