Brother your plants look good it's the start of nute burn it's not extreme. She's just giving you a heads up. Change your solution or dilute the ppm. Lighten up on the nutes. I agree with bird of prey about adding some beneficial microbes you break down your nutrients better for your roots. I like to use Advanced Nutrients Voodoo juice for bacteria and Piranha for mycos. Check out this hydro grower Rangi_Kijani he has some impressive grows and always answers questions about his set up and grows. Pick his brain a bit. Good luck she'll be building buds soon.