I agree with people on the monitoring, if the co2 levels are not near constant the plants don't like it. CAP sells a cheap controller for about $250. It's also nice to have a full climate controller so that you can set fail-safes in case temp or humidity get out of control. If my A/C dies the co2 shuts off and exhaust fans kick on. A properly sealed and enriched room is like a hot rod everything is faster but one small mistake can cause a major crash.
I've not seen any improvement with levels over 1500ppm and it takes VERY high concentrations and time exposure to burn your plants. I run the burner all night sometimes to kill mites. Levels hardly exceed 5000ppm, we saw burn when levels were near 20,000ppm but to even reach that level we had to release a whole tank and run the burner.
If you are not shooting for commercial production I see little need for CO2. Naturally ventilated rooms seem to result in a smaller yield but the buds develop a better aroma and taste. When running a perpetual system it's not a option to cut co2 levels because only a few plants are finishing at a time.
Let me know how cutting down your co2 works LF, putting them outside for a week was night and day for us. If you are able to do that I highly recommend it, something about the outside air and sun does wonders for cannabis.