Doesn't look like nuteburn to me either on the largest oldest leaves. I agree with Reaper and Rusty. Add some Cal Mag and check for rootboundness (roots coming out the bottom of your pot).
Weedhound Reviewed by Weedhound on . my plants got problems please any help hi, ive been looking around for awhile and most of my problems i have solved just by reading but can some one help with this one? E-indoor E-pro mix SCLR-6.4 E- r/o water E-Source water pH Rating: 5