HLG 260 light burn

I’ve got a curious situation going on. In the roughly year that I’ve grown indoors, one of the lights I’ve used is an HLG 260 rspec that I assembled. It’s worked really nicely the whole time. I’ve grown 3 full grows in the room and am about halfway through vegetative on the 4th grow. The light is 24” away and The light at the top growth is 16,000 lux. The light schedule is 18/6. Day time temp is 81 degrees and night time temp is about 70 degrees. I’ve got an exhaust fan at the top and intake tube down low as well as two small fans for circulation. The tent is 36”x18”x60”.

I don’t have a picture but it’s definitely light burn. The inside of the leaves(not the edges or tips) is turning very light and then brown and finally burned and like paper.

My question is this: has anyone ever run into an LED lamp changing spectrum after about a year of continuous use? I’m pretty sure the intensity can’t increase with age and I test the lux fairly regularly to keep track of the grow. The only thing I can think of is possibly the spectrum is changing. Maybe I’m wrong, but the thing I’m absolutely positive is that the leaves are burning.

Three previous 3 grows had nothing like this.

It first started in the corners of the space. The leaves closest to the corners started showing signs first and then it began to show up on pretty much all of the leaves except for the very center of the tent.

Any thoughts?

I took pictures

Do you use any calmag?

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Yes. Typically 5ml/gallon of GH CalMag and the same amount of 5ml/gallon of GH Armor Si

Normally I add that two watering and the third is clear water. I vary the ph between 6.2-6.8. They’re planted in soil

@Hellraiser @Myfriendis410 @Davyg @repins12 @dbrn32 @NeoGroR
Any thoughts?

Reading post before seeing picture, I was thinking you just have a plant that is more sensitive to light intensity. Which is entirely possible.

Looking at pictures, that still may be true. But I’m wondering if this at top or bottom of plant. I can see why you are thinking light burn, but you may have a little deficiency that is making leaves more susceptible to light damage.


I have two 260 kits in my 3x3…. I suspect it’s too much but I’ve never had light burn. And I would not expect light burn to begin on the edges.

I’d consider something chomping on your roots? Do you see any bugs crawling in there?

Any other deficiencies to consider?

Have you tested run off?

Can you share a picture of the whole plant?

I’m 99% sure the spectrum cannot change.


What soil are you using?

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Thank you for the tag. I’m not convinced its light burn buddy. This plant is at the outer edges/corners where the light is at its weakest. I’ve had light burn and it happened to a plant that was directly underneath my light. It grew so quickly it was up and almost touching my light before I realised it was so close. I have four QB260 rspecs up full in an 8x4 tent. They’re around 20 inches from the canopy and no burn. I’ve measured the lux and its between 45,000 -50,000. I think you have a calmag issue. My calmag goes in at 1.5ml per litre which is around 7ml per uk gallon. Leds will lose their intensity as they start to fail and in order to change spectrum some or all of your red leds would need to be out completely. Hope some of this helps mate


Just curious
Why are you adding cal mag and nutrients if you are growing in soil?

I just always have. I figured if there are instructions for soil applications it wasn’t bad.

The soil I use is almost always Happy Frog, the first grow I used Coco Loco but I haven’t used that in a while. I typically mix in something a little bland in the immediate area around the seedling when potting. I don’t transplant, I never have. I just keep watering at a distance from the base of the seedling and let capillary action bring the water to the roots. It’s always worked perfectly, even this grow too.

I don’t have any runoff readings. But outside of the ArmorSi and CalMag I really haven’t started giving them anything else.

Is it more likely that this is a deficiency or overage?

PS- the pics are of the top of the plant.

I grow in Canna soil and I know that there’s enough nutrition in there to do me for a few weeks. Growing under HiD I had no issues whatsoever but growing under leds I started to get problems like yours. Growing under leds does increase your plants need for calmag. Do you have anyway of testing your pH and runoff at all

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Yes, I can test ph and TDS of runoff. I just haven’t done so yet.

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Be interesting to see what your pH is like. I suspect it will be low :face_with_monocle:


Hmmm… interesting

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I suspect a low pH and a high ish ppm. If it’s neither and both are within spec then light burn it is :nerd_face:

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What lux level should I be at this stage of veg?

Something similar just happened to me. I upgraded to the hlg 600 rspec in my 4x4 tent.
The light was at 36 inches with dimmer at 30%.

The next morning my plants were burnt from the lights! My plants looked very similar to yours. I put a humidifier in the tent and got the humidity up to almost 70%.

The next day plants perked up, but the leaves started turning brown and orange in spots where the leaves were burnt. When I upped the humidity it also helped where the heat caused the new growth to look twisted.

Heat stress/Beginning of light burn

Next day after upping humidity and dimmed lights to 20% to baby them

Just my 2 cents……


I was at 12,000 lux when my plants burned.

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