Brown spots on top fan leaves

Hey yall, I'm in the middle of my first grow(3rd week of flower). It's gone pretty well so far, but I've run into an issue I don't know how to identify/fix. I noticed brown spots on the topmost fan leaves about 2 days ago. Initially, I thought it may be a calmag issue finally showing up, since I'm growing in coco but haven't added any CalMag. I've added calmag to my nutrients for the last 2 days, but the issue seems to be spreading to neighboring fan leaves. Any help would be appreciated.

Strain: Black Domina from Nirvana
Medium: Coco/Perlite (60/40) in 5 gal fabric pot
Nutrients: Foxfarm Trio (Hydro formula)

• Big Bloom: 15ml/gal
• Grow Big: 10ml/gal
• Tiger Bloom: 5ml/gal

Feed: 2 times per day
EC: 1800 (2300 after adding CalMag)
PH: 5.8-6.2
Humidity: 60-70%
Temp: 65-75
Light: Spiderfarmer SF 2000

Whole plant
View attachment 20210825_080829_resized.jpg

I have no experience with coco, but I had very similar issues when I tried growing in hempy buckets (no coco but still drain-to-waste). I think the two major contributing factors were:

-LED lights too close
-Too much nutrients (calcium not deficient but being locked out by an excess of something else)

Honestly though I never "fixed" the problem, I just switched to living organic soil and have had much better results since. So take my advice with a grain of salt. Good luck!

We're you able to successfully finish the grow? Or did you change to living soil mid grow?

weedstoner420 said:

I have no experience with coco, but I had very similar issues when I tried growing in hempy buckets (no coco but still drain-to-waste). I think the two major contributing factors were:

-LED lights too close
-Too much nutrients (calcium not deficient but being locked out by an excess of something else)

Honestly though I never "fixed" the problem, I just switched to living organic soil and have had much better results since. So take my advice with a grain of salt. Good luck!

Click to expand...

Yeah they finished but not in the greatest of health. I ended up dropping feeds to the 400-500 ppm range and the damage slowly stopped spreading. Ymmv though, 1800 ppm seems really high to me but different plants and different environments can have dramatically different nutrient requirements/uptake rates.

weedstoner420 said:

Yeah they finished but not in the greatest of health. I ended up dropping feeds to the 400-500 ppm range and the damage slowly stopped spreading. Ymmv though, 1800 ppm seems really high to me but different plants and different environments can have dramatically different nutrient requirements/uptake rates.

Click to expand...

My ppm is about 1000 I think. EC is 1800 microsiemens. I think I'm gonna lower my feed strength since the rest of the plant is really dark green.

Keep the lights 18-20 inches above and lower your nutes.