Light burn?

Hi all, started 4th week of flowering. I see yellowing and marks on top leaves that directly receive light, bottom leaves are just fine. Is this light burn? ( I lifted the lights as high as possible now (around 35 cms - 12 inches)) or is there another underlying condition? Thanks!
 

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Phytoplankton

Well-Known Member
It definitely could be light burn. 12 inches is pretty close, really depends on what the light is (HPS/LED/ brand). What does the manufacturer suggest?
 

ProPheT 216

Well-Known Member
Yes I think you may have cooked that plant. The serrations all seem to be trying to be as jagged and pointy as possible to cool off. 12 inches is probably to close. What does your par map suggest? Probably more like 18 inches. And you just moved to 12 inches?... how close were you before
 
Yes I think you may have cooked that plant. The serrations all seem to be trying to be as jagged and pointy as possible to cool off. 12 inches is probably to close. What does your par map suggest? Probably more like 18 inches. And you just moved to 12 inches?... how close were you before
I think i didn't realize how fast she is growing in stretching phase so the light was about 10 inches away for a few weeks. Now i am at 12 inches.

The light i have is this:

Model: 120W LED grow light
Power Supply: Meanwell / Lifud
Efficiency: 2.6 umol/Joule
LED Bulbs: Samsung LM301B 3500k (512), Cree 660nm (20), Cree 730nm (8), LG UV 390nm (4)
Coverage: Up to 60x60 cm
 
It definitely could be light burn. 12 inches is pretty close, really depends on what the light is (HPS/LED/ brand). What does the manufacturer suggest?
Hi phytoplankton,

Here is the specifications of my light:

  • Model: 120W LED grow light
  • Power Supply: Meanwell / Lifud
  • Efficiency: 2.6 umol/Joule
  • LED Bulbs: Samsung LM301B 3500k (512), Cree 660nm (20), Cree 730nm (8), LG UV 390nm (4)
  • Coverage: Up to 60x60 cm
No suggestion on the box :(
 

ProPheT 216

Well-Known Member
So are you using ratches straps or anything. You should be creative and get the light up as high as u can or start training and bending the plant down. Use zip ties or something... get rid of straps if your using em
 

secretmicrogrow420

Well-Known Member
I think i didn't realize how fast she is growing in stretching phase so the light was about 10 inches away for a few weeks. Now i am at 12 inches.

The light i have is this:

Model: 120W LED grow light
Power Supply: Meanwell / Lifud
Efficiency: 2.6 umol/Joule
LED Bulbs: Samsung LM301B 3500k (512), Cree 660nm (20), Cree 730nm (8), LG UV 390nm (4)
Coverage: Up to 60x60 cm
bra you dont have light burn lmfao i keep my 240 watt led panel like 10 inches away from my tops and yours is 120watt 10 inches away is fine.
 

Daino

Well-Known Member
This is the only thing i use. Been adding 1ml to 2 liters then i upped to 2 ml to 2 liters and recently realized the suggested dose is a bit less but it's not that bad. Also doesn't explain why only top leaves are effected?
Exactly when have you started using pk13/14 all way from seedling stage right through or what??
 
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