Backing off co2 during wk3 of flower

I'll start off w my current setup
A 4x8 tent where my girls reside;
With a 6" filter fan ducted out the top to the bottom of my "lung" tent. A 2x4,
Which houses my dual hose ac and a second 6" fan to pull the cool air back to the 4x8 tent.
A somewhat sealed closed loop system w co2 tanked into the 4x8 at 1200-1500ppm.
So far a 20lb tank has lasted 8 weeks!
I want to cut the gas and go to a vented situation about week 3 of flower. Apart from bringing the temps down from 82-84 during daylight to 77-80 over one dark cycle.

Is there plant shock to be expected with a change like this?
Should it be gradually changed over a few nights?
And finally is this a bad idea? I mean is it more productive to keep the gas untill the flush, like I'm pulling the rug from underneath them by removing and venting?

I want to cut the gas to vent out heat and smell farther into flower. I like to run cooler temps as buds develop and venting is much cheaper than ac.

I have been really enjoying this knowledge that is on this board.
It's helped me connect the dots on issues I have been having my first few goes. Issues I didn't know I even had!
Lol

Thanks for sharing.

Edit: this probably should be in newb questions or general growing section.

A 4'x8' cooled by a 6" running Co2...interesting.

What kind of lights/wattage are you running in there if I may ask?

I'm using leds that came my way,
A kind 750 -around 430 at the wall
And a mars II 1600 - pulls about 600 at the wall.
Veg w a cmh 315

Worth a peek for anyone running Co2.


Next run I'm going to try no Co2 during stretch.