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COB Cxb3590 3500K burn leafs 14 inch


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#1 olsqueak

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Posted 24 November 2017 - 10:12 AM

Hello,I use my new cob cxb3590 3500K 2*50watts for a long times rooted clones.Distance 14 inch from top plants but now i can see than some leafs are burn,the cob must be too much closer.
What's do you think it's a safe distance from top plants for 4*50watts COB or 4*100Watts (I can use dimmer 50 to 100watts). ?
Have good vibes.
Thank's before for your help,friendly,Olsqueak.

#2 Hempyfan

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Posted 24 November 2017 - 11:48 AM

Well get the raising them lights.

A basic light tester is not accurate with this but it will give you a concept of intensity determine the intensity at lower levels of your plant. It will give you an idea on how much you will lose at the lower level by raising it further.

Use that information when managing your plant such as in terms of clearing the bottoms and stuff

Question is it light intensity or heat in humidity issues a picture will help much
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#3 Gardener

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Posted 24 November 2017 - 12:08 PM

Raise the lights if you want to relieve the plants from their stress.

How far to raise the light is somewhat dependent on the light itself. What is the power of the LEDs in the light? 5 watt LEDs will burn a plant at the same distance that 3 watt LEDs could safely grow a plant. I have a Platinum LED P300, which is ~180 watts total, but the LEDs are 3 watt. They recommend 18". (I have light-burned some leaves by putting the light too close.)

If your LEDs are 5 watt, you might try at least 24".

#4 Balarama

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Posted 24 November 2017 - 12:55 PM

I have them @40W each and around 1m above the canopy when clones are put in their final pots.
So adjust the height to at least 20-24"

#5 olsqueak

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Posted 24 November 2017 - 01:12 PM

Now the COB CXB3590 3500K run at 2*50w with low dimmer,if i use at max power I have 4*100watts.
Balarama if I well understand I must keep at 20 Inch Mini and 24 Inch Max for 4*50watts.
Gardener I have 4pcs 50 to 100watts cxb3590 72v 3500K with 2pcs HLG-185H-C1400A.I think 24 Inch is a Safe Distance for the plants ?
More Watts in COB equal more distance from top plants like hps ?
If I use at max Power for flowering period 4*100watts I must Move the COB at more distance from top plants ???
I order 4 Vero29 36V or 38V 3000K for run 50w*8,hope I make the good choice for quality price.
I hope you understand my bad english.
Have good Vibes.
Thank's All for your help,friendly,Olsqueak.

#6 olsqueak

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Posted 24 November 2017 - 01:52 PM

https://www.opengrow...1043_634248.jpg
https://www.opengrow...1043_182827.jpg
Picture from burn leafs.
Thank's all from your help.
Have good vibes,friendly,Olsqueak.

#7 webeblzr

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Posted 25 November 2017 - 09:01 AM

I think you may be focusing on the light as the issue, and it may be, but it seems to me, there is leaf above the so called burned leafs.
Leaf can show that, if a fan is blowing directly on or at them.
Where I may use a fan in the springtime as humidity builds up, but I never blow on the plants, at a wall, at the floor, or at the ceiling.
A blowing wind will cause leaf to transpire it's moisture to quickly, in indoor environments.
In the second pic, it seems to my old eyes, there are leaves above the *burnt ones* that look fine.
IF, this was my plant, it would be in a bigger container, it have no wind blowing on it, and my LED's would be up tight in the ceiling of my tents.
Best of luck man!!

#8 Balarama

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Posted 25 November 2017 - 10:59 AM

These are not burned leaves from light.
Probably some leaf infection or pest, maybe deficency or lockout, overwatering? ...definitely not light burn.
Take off these leaves, use gloves and don't touch your plants with them.

#9 ledfoot

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Posted 25 November 2017 - 03:33 PM

Now that I see the pics, I have to amend my PM and say the COB positioning is not a problem here.
It is something more biological.

#10 Pedro Bann

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Posted 25 November 2017 - 06:32 PM

to me it looks like unhardened leaves gone straight under strong lighting and the newer leaves are OK, at 50w per COB I could get to 10cm from the plant tops before light bleaching.
2 feet away defeats the purpose of having strong light...

#11 dieseldog381

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Posted 25 November 2017 - 06:37 PM

Hey, Ols, I'm not familiar with the COBS, but maybe someone here can help out with your specific questions.

My two cents with LEDs, RAISE THEM WAY UP, especially with seedlings, I'm talking 3-4 ft!!! Your plants will be harmed more by too much light, than by not enough. As you see how the plants respond, gradually lower them. But I've run Silverfields, Jack, Holy Princess, Bubba Kush, and C99, and all did beautifully with the lights MUCH higher. Look at some Colorado commercial grows and how high they mount their LEDs. Manufactures sell PAR ratings at 18-24 inches to sell lights or just to illustrate.

I run a Platinum 450 and a 600, in an 8 ft grow space, and if I mount them flat on the ceiling (had too with Kali Mist!) I still can get a bit of bleaching, they are extremely powerful!

LEDs can also create nutrient issues you won't see in HPS, that mimic all kinds of crazy stuff. What looks like burn, may be nutrient deficiencies, particularly cal mag and phosphorous. Because heat is not an issue, I also found they SOMETIMES, not always, use less water, which can be strain dependent.

It took me six months of experience to get my LED grow dialed in, and I burnt the heck out of a few grows following the 18-24 inch guidelines The owner of Platinum told me their LEDs can really use up the cal mag, so I doubled it, as cm rarely harms plants. My Holy Princess mimicked light burn AND NUTE BURN, twisted crusty leaves, yellowing, so I kept cutting nutes, exactly the wrong thing to do. As soon as I doubled up my bloom nutes, it cleared right up.

Do they look like this? https://www.google.c...NASFejvhZJzvAM:

Good luck to you, you'll really enjoy LED bud!

#12 ledfoot

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Posted 26 November 2017 - 02:11 PM

Now that you mention it, dd, I have wilted healthy plants going to 5000K COBs from T8 fluorescents. They drooped badly, I had just built the COB luminaire and I blasted the vegging plants. I haven't used it since, actually--I put the plants into the flower room after that, as I recall.

I believe magnesium is the needed part of cal-mag in an LED grow so I add epsom salts (MgSO4).

Edit: I meant to credit Pedro Bann as well. My vegging temperature was a little bit lower when I transferred the plants to the COB array area but the leaves drooped like they were cold.

Edited by ledfoot, 26 November 2017 - 10:45 PM.