OneHitDone
Well-Known Member
So, if heat is not the cause - what in the light spectrum of led is the cause of bleaching at high intensities?
Cause of plant bleaching with led?
- Thread starter OneHitDone
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dandyrandy
Well-Known Member
I used to have that problem until I switched to white LEDs.
captainmorgan
Well-Known Member
Blue
churchhaze
Well-Known Member
I think it has to do with the high absorbance of red and blue by chlorophyll. If you use only R+B light, the first layer of canopy absorbs almost all of the light, causing it to become over-saturated. Also, too many high energy photons (too much blue) could be causing destruction.
It also might have to do with a deficiency that was hard to notice under less extreme conditions. (iron or magnesium maybe?)
I'm not 100% sure. I tend to get burn with white leds when the tips get too close to the light (straight up brown/gray/black), not bleaching.
It also might have to do with a deficiency that was hard to notice under less extreme conditions. (iron or magnesium maybe?)
I'm not 100% sure. I tend to get burn with white leds when the tips get too close to the light (straight up brown/gray/black), not bleaching.
harris hawk
Well-Known Member
nutrient issue
PSUAGRO.
Well-Known Member
I agree......tight lens angle doesn't help either. Never had an issue with the 65w Hans panel using reflectors though.
guod
Well-Known Member
OneHitDone
Well-Known Member
That can't be it - that one says if occurs at all light intensities.
Someone needs to work up an LED that could act as a true "solar simulator"
Positivity
Well-Known Member
diffusion helps...raise the light or lower the intensity. Something about the spectrum isn't exactly right. Works great, but not perfect...its why I laugh at companies banking on the yellow similarity. "Harness the power of the solar spectrum"....baloney. Cobs are very very good though....my favorite yet..
OneHitDone
Well-Known Member
Are there led diodes that generate adequate UV and IR?
You would think with individual diodes and proper output information one could blend a bunch of individual led's to truly reach a sun like spectrum.
You would think with individual diodes and proper output information one could blend a bunch of individual led's to truly reach a sun like spectrum.
Positivity
Well-Known Member
yeah...i don't know what the holdup is on that. Leds are still maturing I guess. Uvb is still hard to find and last I remember had horrible outputs versus cost. Different companies specialize in different spectrums, you'd have to get them to work together. Or piece it together yourself like heliospectra...
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Positivity
Well-Known Member
I actually jumped the gun...are you talking about bleaching as in white tips on bud tops or overall plant lightening..
Last time I saw white tips i had a top really close to deep reds. I've seen my 90w prosource ufo do it easily at low power. My old glh spectra did it bad with its dual chip setup. I've seen my cobs do it, but it was a top within 2" of a 3070 at 10w
I was more talking about an otherwise healthy plant losing overall color and lightening. See that all the time with cobs and it was recently on my mind..seems to happen a little prematurely compared to other light sources
the dopest
Well-Known Member
I'm in the nutrient issues camp. Mine started yellowing on my first LED grow with 3k CXA3070s and I pumped up the nutes, after about 3 days, they were not only greener, but growth rate took off in a good way. Now my plants are happy and healthy and starting to put on weight. I am running about 42w per sq ft in a 4sq ft cabinet and use the GH Flora Micro and Bloom in the lucas formula with tap water. I just added KoolBloom to the mix last week but other than that, nothing but 5.5-6.0 ph and lucas.
OneHitDone
Well-Known Member
I was referring to the "bleaching" that is always mentioned under too high of intensity in the diy posts
You don't ever here of bleaching even under DE1000W HPS
You don't ever here of bleaching even under DE1000W HPS
Positivity
Well-Known Member
thanks for the clarification..I don't remember as many bleaching issues either. I had a 600 in a incredibly small area once..think those pics were on overgrow back in the day..
Anywho...Backing off the light does the trick, it's just light overload. These cobs are very directional, straight down versus hps 360..
If I had a par meter I'd fire my 600 up and do a quick comparison. Won't be dropping cash for one anytime soon though..
wietefras
Well-Known Member
I had bleaching under a 1000W Gavita DE.
It's just that normally HPS lights are kept well away from the canopy because the radiating heat from the lights is damaging already before the light intensity gets too high. So with HPS you know quite quickly that you are too close because the leaves start curling up. In this case I simply ran out of space. Although later I cut a hole in the tent ceiling and lifted the light right to the top of the tent to fix the issue.
The light was somewhere between 60cm to 70cm (24"to 28") above the canopy and then this happened:
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