m0useanswered grow question a year ago 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!