When using C02, didn't you say a while back that you pushed the ppm up to 750? Or are you using 600 ppm regardless?
yeah, i tried playing around with input strength while using co2 and never saw much difference in growth so just went back to 600 ppm with a 750 co2 set point and a 50 ppm dead band with 6k on usually 10 plants.
i'm setting up my first personal room now since my move and will have much more intense lighting so it will be interesting to see what i will have to input.