i wouldnt up your nutrients just cause your using cO2 i use cO2 in the bottle under 10 psi.... but dont get me wrong when using cO2 your tds/PPM will raise like 300 so u have to add that to your nutrients somtimes u wanna feed less when using cO2 but in some cases your buds are breathin the cO2 and r using there energy ( nutrients faster) so its case by case... but if your ppm's are like 1500 n your cO2 is on now your at 1800 ppm which is dangerously high so i would play by ear