How powerful is my light!?!

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ecuaodor_s

Member
Hi all,

I bought this quantum board from a local manufacturer, here is the information on the box:

Description: Quantum Board is an advanced LED lighting system with a wide spectrum.

The system consists of the most efficient Samsung LM301B diodes on the market, with a 3500K shade suitable for all growing stages.

Model: 150 W
Electricity usage: 120W
Power Supply: Meanwell / Lifud
Efficiency: 2.6umol/joule
LED lamps: Samsung LM301B
Coverage: up to 60x60 cm (2x2)

I've tried to put it respectively 60 - 100 - 120 cms away from top of the canopy and it burned my plants! Since there's no more room in the tent i opened up the top of it and placed the lamp like in the picture. Finally the plants are recovering and you can easily notice the left one is much darker than the right one since i assume she is shorter. At the moment the distance is 175 cms away from top of the canopies!!! It's like 70 inches away. Is that normal? Is there something wrong with this light??
 

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E

ecuaodor_s

Member
Jjgrow420 said:
It's 120w light....
It should be between 8-18" above your canopy. Introducing plants to higher levels of light should be done gradually over a few days.
Is there a dimmer on it?
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No, there's no dimmer. Yeah it's 120w it doesn't make sense! How did it burn them so bad? Happened also with my first grow and i didn't know it was the light back then now i am 100% sure. Is there something like rough light? Maybe they used cheap materials even though they claim it's Samsung?
 
E

ecuaodor_s

Member
MickFoster said:
I don't think it's light burn. Looks more like a deficiency. What is your medium, nutes, feeding schedule, etc?
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Light burn 100%
Tolerance Break said:
Not a light issue. Looks like a deficiency of some sort.
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Thank you and i agree, it sure does look like a deficiency of some sort. I assure you sir, i have gone over many options and the only ways the plants recovered was when i finally moved the lights further away. There might be additional problems sure, but the light is the main one, i am convinced.
 
E

ecuaodor_s

Member
MickFoster said:
Put a lux meter on it and you'll know for sure.
Good luck.
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I only have one as an app (the one migro suggests) and it shows both lux and ppfd levels way under recommended but i have no idea how reliable the app is.. Regardless, something tells me this light is not built for a tent sized 2x2
 
7CardBud

7CardBud

Well-Known Member
Jjgrow420 said:
...and here lies your issue. There's something likely wrong with your medium. Too much nutes.... Imbalance.... Improper ph... This is where I'd start my investigation.
More Info on your soil...?
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Could be the other usual culprit using LEDs, low soil and leaf surface temps. Low transpiration and reduced nutrient uptake.
The light is not really the direct problem, but can contribute. You were correct to move the light up, sick or weak plants will not respond well to intense light. When I have weak plants I reduce the light intensity to the range a young seedling would use until they recover.
 
Hollatchaboy

Hollatchaboy

Well-Known Member
ecuaodor_s said:
Light burn 100%
Thank you and i agree, it sure does look like a deficiency of some sort. I assure you sir, i have gone over many options and the only ways the plants recovered was when i finally moved the lights further away. There might be additional problems sure, but the light is the main one, i am convinced.
Click to expand...
Your light is not the problem. The reason why they recover when you raise the light, is because you're not pushing the plants as hard.

You can't just increase light intensity, without making adjustments to the other limiting factors.
 
E

ecuaodor_s

Member
Hollatchaboy said:
Your light is not the problem. The reason why they recover when you raise the light, is because you're not pushing the plants as hard.

You can't just increase light intensity, without making adjustments to the other limiting factors.
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Thank you for the explanation. I am a newbie so i don't have much hands on experience. This is my 2nd grow attempt with this light (i made it to flower first time but half the time i was using an aquarium light) and in both cases i have the same problem. Before i bought this light I had a 10w aquarium light and the first plant grew quite healthy to a reasonable vegetative size that actually made me buy this light for proper flowering. It also burned the plant and it turned hermie (or was hermie to begin with but it doesn't matter leaves were totally burned) and it looked like nute burn.
 
E

ecuaodor_s

Member
Doug Dawson said:
What medium are you using? What are you feeding them, how often and at what strength?
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I am using soil. The brand is johnny green. Since it's quite easy to confuse nute burn with light burn i avoided using nutes in this grow (i used nutes twice - standard NPK fertilizer - 1/3 of the recommended dose just to be on the safe side and that's all, rest of the time just plain water )
 
Hollatchaboy

Hollatchaboy

Well-Known Member
ecuaodor_s said:
I am using soil. The brand is johnny green. Since it's quite easy to confuse nute burn with light burn i avoided using nutes in this grow (i used nutes twice - standard NPK fertilizer - 1/3 of the recommended dose just to be on the safe side and that's all, rest of the time just plain water )
Click to expand...
This is what light burn looks like.....

Dealing-With-Light-Burn-On-Marijuana-Plants.jpg


Does it look anything like what you got going on?
 
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