Need help with designing a quality grow box

Hey fellow soon to be hopefully growers,

I was thinking about creating a DIY grow box myself as I'd like that more than a grow tent, am going to model it after this one. (Someone's else grow box design)

The dimensions of the box are 4’W x 2.5’D x 5’H. Every surface will have reflective material on it.





My questions are, if I somehow implement co2 enrichment throughout the plants life cycle, do I need circulated air for the plants through fans/vents? Would I be able to keep this air-tight or as tight as possible?

I would have the heat cooling separate to the space within flower chamber. With a carbon filter in the electric chamber, intake on the left of the light for airflow.

And with the co2 enrichment I was going to have it somehow from the top and maybe a fan or two inside to move it more around.

Would I be able to keep the co2 PPM at around 1200-1500 with this sort of setup? At that co2 PPM level, will 400w or 600w HPS light fixture with all needed gear be fully utilized by the plant?

How would I go around controlling the temperature and humidity in the chambers?

Will be using a iPower T5 for the veg chamber. This is my first time ever with growing myself and I know I should master other aspects first and try something smaller or simpler for my first few grows, but I've always been kinda of a all or nothing type a guy. Not a great trait.

Thank you for any input, info, comments.

I use a cabinet roughly the same size.
My advice would be to forget about co2 in it.
You won’t ever make it air right enough for the co2 to be worthwhile imo.
It’s not necessary for such a small area anyway
If your not against spending a few bucks doing it right the first time I’d recommend using leds and it will be far easier to cool and you could probably get away with a 4” cpu fan out .
Mount the driver(s) on the outside of the cab not in the growspace.
Good luck

Thank you torontoke for your reply and input. I've read a bit about HPS and LED lights, saw a lot of LED don't put out the wattage they advertise and it sounds like a nuisance. But really if it's more beneficial I don't mind spending more bills.

What size smart pot in gallons do you think they should be for the flower chamber? I'm going with 3-4 plants at a time.

Go in the led section and read a bit.
There are many options but for small spaces u need all the temperature help u can get.
I use 2 pcb leds at about 90watts each.

Honestly it doesn’t really matter what size u use or how many u can use 10 1 gals or 8 3 gals and your yield will be similar no matter what. It’s gonna come down to canopy size/wattage