400 watt MH Vs. 2000 watt LED +Adding C02 to grow tent.

Hey all im gonna run c02 in my little 2'x3' tent. Currently I am running a 2000 watt LED but i only used it to veg plants for outdoors.
I have a 400 watt MH bulb and dimmable ballest Would this be better to help my plants absorb the c02?

The MH set will consume a little more power than the 390w led light. Gauging the led's hidden efficiency is difficult though. I reckon the MH might make more usable light per watt.

6 foot really doesn't need a 400 so you will likely sit at 250w. I don't know how the 390 works or if it's been in that tent already. Perhaps you can manage it's heat at 390 while the MH can't run at that so must be run at 250 and isn't the best colour to flower with, if you intend to flower

Sounds like a vote to stick with the LED. I would have to exhaust more often with the HID and that would cause me to use more c02.

Tent cost much? There is no reason to put the LED in the tent. You could cut a window in the roof. Maybe board the roof externally, so the light unit can look down through the window. A window just a tiny bit smaller than the light. So the light just sits on the board. Looking down through the hole. This means the heat of your light places no demand on your extraction system.

I can't see CO2 having any valid use if you need extraction. Some industry somewhere is able to say their waste gas is actually a product if you buy it. So they can make more. Which isn't a good prospect for the future of your genes. Especially if you just let all that gas go.

We breathe out loads more CO2 than a little tent can use. 1000's of ppm. Using that is a good goal.

Unless you have years of experience it generally offers no gain. Just problems.

The tent was next to nothing (45$)I dont have the ability to run it closed it would be too hot in there.
What does needing extraction mean?
C02 has no valid use?
I have close to 15 years of experience is this enough to offer "gain"?