Help Connecting 2 rooms together!

Ok so I just built a veg box next to my other box and so now I will have a flower and veg box. My flower box has my AC and Co2 in it.
I just put ducting running from my flower box to my veg box and then ducting back out of my veg box into my flower box.
My question... Will the Co2 from my flower box go into my veg box? and is it bad for Co2 to run during the night time under flowering plants? I know its a waste of Co2 but I dont really want to go get another co2 tank and regulator for my veg room.
Only reason I have both rooms ducted together is because my veg room gets a little hot and the ac is in the flower box.

I don't see you having an issue, other then if any light from the veg box can get back to the flower box.

Vegging plants don't really need much extra CO2 either. I doubt it'll hurt. Just not really needed.

Remember your Dry ice? The smoke IS CO2, and thus weighs more then air. Therefore it drops. CO2 from a tank is the same. It'll collect on the floor if nothing pushes it back up into the room.

SO,.. Keep in mind, if your line (hose) to the veg box comes out of the flower box at the bottom. Your veg plants might get more CO2 then the flowering plants. Same the other way too. If the line out of the VEG going back to the flower box is coming out of the bottom of the box it'll move more CO2 back to the flower box.

Should be interesting to see if it works out.

Oh and by having both boxes connected. You risk cross contamination should you ever get bugs. So be extra careful about that too.

Keep in mind that your flowering girls are expeling Co2 at night and breathe it in during the day. Don't want to make a toxic environment for them. And keep in mind that vegging plants need a higher rh than the flowering girls. 60% in veg and 40% during flowering. High humidity in the flower cycle can lead to bud rot. Good luck.

Okay well eveything is working fine... Only
problem I'm having is my rh is around 48% which is kinda low for vegging. But the plants look healthy..