AK48 strain, yellow blotches on upper fan leaves

Hey guys, got about 12 plants run in a large tent under 1200 watts. Over the past few days I have noticed that one of my AK48 plants has started forming yellow spots on the outer surface of some of the top fan leaves. Currently using floranova bloom, liquid koolbloom, floralicious plus, and florakleen to flush the soil periodically through the grow. Adding amounts recommended by GH, and no more than that. Water pH'd between 6.1-6.3 as recommended by a professional grower. Can't seem to pinpoint the issue, does anyone else here have an idea? I attached a picture below.

bump... any ideas?

Had something like that and cal/ mg fixed it.

Btw I just finished a run with a couple ak 48s mixed in. They love nutes. Are sensitive to cal/mg/fe def but will pack weight on the longer you go . Watch ur pH too

what's the NPK of the nutes you're using? i suspect the blooming fertilizer you're using is lacking something. GL

i keep my ph around 5.4-5.7 ish and they are right in the zone to intake all the micro nutrients ,so think about lowering your ph and see if they start picking up.. KEEP ON GROWIN

Whats on the underside? Look for mites.

I tried fixing this but it got progressively worse. I went and bought calmag with no luck. I found out from my hydro shop that it's a fungus that all the growers around here are getting. It causes the leaves to get dark brown spots and claw upwards. Now i'm using a fungicide and the symptoms are starting to improve. Crazy stuff.