Slight browning on leaves

After looking at your diary and looking further into your npk of your nutrition. Your plant wants more potassium. Nutrition burn like others are saying the tips turn brown, and curl up and in. Your tips are brown and straight. Which is a lack of. Now your plant is getting the rest of what it needs. Just wants more potassium would be my answer after reviewing.

Your diary says the EC is 1.6, that is a bit high for plants of this age to me. I think this is nutrient burn. Lower your EC and it should correct itself and stop spreading. So in short small cause of concern but easily correctable. As for PH, I think keeping it around 6.2-6.5 is ideal, this allows you some buffer room should the pH drift one way or the other. 5.8 is to low and 6 is descent but on the cusp. All hydro nutrients are available to the plant for immediate uptake and they can do this in between the ranges of 5.8-7.0 PH. Just confirm your feed is giving all the micros needed "Fe,Mn,Cl,B,Zn exct" as well and secondary macros like "Ca S Mg" Best Of Luck!

Hola amigo he leído su diario. En primer lugar puedo decir que su ec no está muy alta sólo bajaría unos puntos a 600ppm = 1.2ec luego también bajaría el ph a 6 e iría aumentando a medida que avance en etapa de floracion. Creo que también me preocuparía por los tallos morados esta indicando estrés y mi deducción es que su luz esta un poco cerca, la planta transpira por las puntas de las hojas y creo que también puede ser motivo de sus quemaduras. Buena suerte

Those are burnt leaf tips caused by excess nutrients. In short nutrient burn. Try to skip or reduce feeding in your next coiple of feeds. Those burnt tips won't recover but the new leaves will be fine. Good luck with the rest of your grow, nothing to worry about and very easily fixed.