Ducting and ventilation question

Setting up an indoor grow in a room approx. 18'x8'x7'-8' tall. I am fairly confident in my plans for setup, however...
I am trying to get an understanding on the ducting attached to filters and fans "thing". Is it just to cut back on smell?Is it necessary (and why)?

Ps- I'll have several oscillating fans inside room, as well as an AC, dehumidifier, and heater. ALSO, I understand using to cool hps lighting, but I'll be using LED lights (at least for the sake of the question

It is not just for smell abatement. Adding ventilation to your room also serves to bring in fresh air. In that fresh air is co2 for your plants. Also bringing in fresh air gets rid of excess oxygen produced by the plants, moisture from evaporation, helps reduce mold growth, and to remove heat. LED lights do produce heat. Not as much as lets say an HID setup, but they do produce heat. You can grow in a sealed environment, to do so you will need to keep the heat down, humidity down, and provide a source of co2.

They also remove dust and particulate from the air but you don't necessarily need carbon filters for that if you are not worried about odor. Like said above you will either need adequate air exchange for Co2 or supplement Co2 in your room in which case you will want it to be sealed for efficiency reasons. I run a sealed Co2 supplemented room and as far as O2 I have never seen or heard of an issue with it other than lack of O2 at the root zone. I could be wrong but to my knowledge to much O2 i have never heard of and I open my grow space usually right before lights out to inspect my plants (its a small space 4'x6'x8'). My Co2 shuts off an hour before lights out to help lower the ppm as plants give off Co2 at night and high levels can be dangerous so venting the Co2 out a night may be a consideration that you need to look at depending on your setup.

With all your questions are you sure you want to start such a big project ?
I anticipate a lot of issues your first few runs
It took me 3 years to dial in my rooms

If your asking why do people use ducting, simply because its easier to carry the air than mount a fan directly to a hole in the wall or to a filter.

Herb & Suds said:

With all your questions are you sure you want to start such a big project ?
I anticipate a lot of issues your first few runs
It took me 3 years to dial in my rooms

Click to expand...

^^^ good advice