Running out of co2 in sealed room

Well I didn't run out of co2 but I was doing some work in my sealed flower room yesterday and I unplugged my tank since I was going to be in and out for a while. Anyways I forgot to plug back in the tank regulator and just noticed it now. So my tank was not running for about 10 hrs of on light time since my lights go on at 4pm, I unplugged the tank at about 10 or 11pm yesterday. Just now my room was at about 400ppm and I swear when I was looking at the buds they didn't look at happy and glowing like they did yesterday but the pots where bone try yesterday and the plants looked like they were just spitting out trichs, they where glowing at day 27... Has anyone else that runs a sealed room w/co2 notice the difference in the plants relatively quickly when they weren't getting co2?

that's a barometric pressure thing i bet div.
running CO2 in a closed system would increase that right? so when the system was off for 10hrs it was like bringing a deep sea fish up to the surface, fish can't de-gas but plants can.
sea level atmospheric pressure= 1013.25 millibars