Random yellow leaves 3rd week of flower?

[MHOGSMI]

3wks into flower. Blueberry Headband. Some fan leaves dying off and turning yellow i feel way too early. Not happening to any other plant in my rdwc system.
Thoughts?

Cyco nutes.
Ph 5.9
Temps low 80s.
Rez temps high 60s..

Thoughts?

 

[TripsRabbit]

Is there a fan right there?

 

[smokedareefer]

I see purple

 

[MHOGSMI]

Yes. I'm using blurple lights/leds. There's a fan in the corner of the room. But why only a few leaves in the middle? I sprayed with a really light N feed on that plant only because the only thing I'm thinking is that it still wants more N.....?