Light burn, Heat Stress or Something I'm missing?

[Trogoliath]

The sick leaf is getting sicker. The dull green color patch has now become brown(ish) in color and spread to the other side of the leaf!

What is this thing? how can it still be light burn after I've moved the lights 3 inches away yesterday night? I didn't think that was possible with LED lights...

Perhaps it's calcium deficiency (but I used Cal-Mag in yesterday's watering)?

What if I cut the problematic leaf - before the symptoms spread to the other ones? Would the plant take the stress this early in its life?


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Journal link

Strain: Northern Lights AF
Current State: Week-3 Veg
Medium: Soil (Fox Farm Ocean Forest + Perlite)
Current Pot: Airpot 1 Gallon
Light: DiamondSeries DS200 LED
Temp: 70-80 F (~ 20-27 C)
RH: 35-50%
Water: RO filtered water
Watering Cycle: whenever pot is dry and/or light to carry
Nutrients: [Available but not used yet] Botanicare Pure Blend Pro Grow 3/2/4 + Pure Blend Pro Bloom 1/4/5 + Cal_Mag + Liquid Karma
Misc Info: Open Closet Grow (no ventilation or air filtration installed yet).

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[Lester Freeman]

There are no signs that the effected leaf is spreading to the other leaves. I think you kind of pinned the tail on the donkey. It sounds like with no air circulation and an intense LED light that you could easily see some damage to tender leaf tissue. It seems it growing out of it.
It sounds like, depending on the wattage of your light, that your light is also a bit too close. Definitely want to get some air circulation in there and consider moving the light away by a couple inches or so. I believe depending on the plant that the LED Diamond DS200 should be 8-48 inches away from the plant.

I don't grow indoors nor am I an expert on lighting, but just thought I'd offer some kind of response .

 

[brightlight]

Light burn would be more likely to appear at tender developing leaves at top of plant, not a lower leaf. You may be right about the heat stress because that leaf looks dry and crispy. If you moved it up 3", does that mean it was closer than 3"? I use LED and like approximately 10" to 15" distance for young plants. You can cut off that leaf without any risks to the plant if that's what you wish to do.