Hydroponic leaf problems - 6.2-6.4 ph. Humidity 75-85% early-middle flowering (I can't lower the humidity). PPM 750-780. Tap water was 140 ppm. GHE fe

It looks like calcium deficiency, but it cant be. I add GHE cal-mag always 2ml per 5 liters. and FloraMicro also have 5% in. Appears only on the middle-upper leaves, but much more on the top. Could this be an excess?