Carbon air filters

If i hook up a carbon air filter, should it be circulating free air in room, or pumping filtered air out of the room? I know it sounds like a dumb question, but what the hell, I don't know the answer. Also, when to plants start to smell strong? During veg, flower? How late in cycle? Any help appreciated

Hook your filter to the top of your tent with it always sucking the air out of your tent. your inlet fan should always be pumping cool air from the bottom. Your filter not only gets rid of smells it also gets rid of heat to help staberlise the temperature in the tent.

What do you mean by how late in the cycle?

my girl started smelling a bit more around week 4-5 of flowering, or so it seemed

If you have a small setup it will start to really smell 4-6 weeks into flower, if you go big it can be overwhelming to someone else by 2 weeks into flower, the filter is personal preference i actually do one recircing in the room and another one on the outlet as well that way its lessening it in the room and then removing the last of it as it leaves

Its normal i've noticed your doing a cfl grow in which case the smell will not be as intense due to cfl's not giving off much heat to make the plant sweat. The more the plant sweats from heat the more the smell. What watt you using and how many cfls

I'm using 1000w mh in a 3.5x7.5 closet. When I flower I'll be using 1000w hps. I was actually thinking about putting a filter on my portable AC exhaust. Good or bad idea? I have the tube sucking air from another room through the tube and out of the room. The air in tube never touches my closet. I can rearrange things, but this method kept temperature lowest. Keeping my temp at 78f. My fear with sucking air from room through tube and out of room is overworking the AC.
Thanks to all for advise so far!!!

Also, risk-reward-quality, should I try and make my own filter or just pay the $80 and buy one? Or two? 12 plants in 3.5'x7.5' area

Buy one for 12 plants I'm using a 12 inch filter for 15 plants in 15 litre pots and had no problems, not sure about the AC thing I'll ask some people and get back to you on that.

Thank you!

I think the AC is a good idea, your talking about a closet not a small box so it should be enough air flow for it not to overwork, by anything noticeable anyway.. besides your running a fine like on the 78degrees once you start getting into the 80's some strains can take it but for indicas you start to notice heat stress

Thanks for the input. Yeah, I was hitting high 90's without AC. I hooked it up and got low 80's. The only way I got it down was to suck air through tube from out of room and pump it out. My 4" climate control airflow into the room and my 6"AC exhaust are my only forms of ventilation. And 2 12" oscillating fans. So you think 1 good carbon filter on AC exhaust will control air leaving room? Also, will a hepifilter attached to a box fan help control smell inside room? Or do I need another carbon filter?