Lighting Any cob users measure lux at canopy?

[Animatey]

I realize par is a better measurement than lux for plants, but a lot of us probably still have lux meters lying around, not to mention that lux meters are nice and cheap...

Lux should still give an idea of how even/intense the lighting is.

Anyways, I'm wondering if any of you cob users or autocob users measure lux at canopy?


I have a 3 bears og that cannot seem to go above 15k lux without yellowing of the upper leaves.

Anyone have any lux data that they could share with us from successful grows?

 

[MrOldBoy]

I realize par is a better measurement than lux for plants, but a lot of us probably still have lux meters lying around, not to mention that lux meters are nice and cheap...

Lux should still give an idea of how even the lighting is.

Anyways, I'm wondering if any of you cob users or autocob users measure lux at canopy?


I have a 3 bears og that cannot seem to go above 15k lux without yellowing of the upper leaves.

Anyone have any lux data that they could share with us from successful grows?

Funny you mention ...... LUX means nothing under a COB you need a PAR Meter but having said that 3 Bears does NOT like a lot of light compared to others - I had same issue with my 3 Bears until I realized she did better in the corner than under the direct light - she likes PAR around 525 verses others 600-700 range ......

3 Bears on the right - strawberry Nugs left

pic does not show but bears is on far right side of light and Nugs is directly under

 

[Animatey]

Funny you mention ...... LUX means nothing under a COB you need a PAR Meter but having said that 3 Bears does NOT like a lot of light compared to others - I had same issue with my 3 Bears until I realized she did better in the corner than under the direct light - she likes PAR around 525 verses others 600-700 range ......

3 Bears on the right - strawberry Nugs left

pic does not show but bears is on far right side of light and Nugs is directly under

View attachment 1136617

Hey man, thanks for the reply!

I have read that it's possible to convert lux to par for cobs. There was a few guys over on another forum that used lux and par meters and figured out the conversion factor for various colors and CRIs of cobs LEDs.

They said generally you can take a lux reading and multiply by .014 and get par for 3000-3500k cobs that have 80-90CRI.

36000 lux is about 500 par.

I can't really get my 3BOG over 15000 lux which is only approximately 210 par (if the conversion factor is correct).

I'm using 3000k @ 80cri and 50 watts in my 2x2 seems to be all she can handle, which is bizzare.

The leaves get yellow and the serrated edges get curled up. This doesn't happen on lower growth, just the stuff at the top directly under the lights.

Humidity, temps and pH, etc. All pretty much perfect. She never had a problem until the light intensity went up.

I noticed people grow a single auto with a 55 watt auto cob, and seem to do OK. However, I can't imagine the lux reading would be very high... So I'd be interested to hear what people measure at canopy with cobs.

 

[Animatey]

@BigSm0 I'd be interested to hear if you've ever done any intensity measures with a meter of some kind?

Autocobs seems to be fairly low wattage, yet they seem to be capable of inducing light stress if too close or too many, so I think this info would be really interesting.

 

[Simplicio]

I realize par is a better measurement than lux for plants, but a lot of us probably still have lux meters lying around, not to mention that lux meters are nice and cheap...

Lux should still give an idea of how even/intense the lighting is.

Anyways, I'm wondering if any of you cob users or autocob users measure lux at canopy?


I have a 3 bears og that cannot seem to go above 15k lux without yellowing of the upper leaves.

Anyone have any lux data that they could share with us from successful grows?

I've been getting light burn from about 30,000 lux.
If I get the COBs closer than 30 inches, I get plant stress.
The brightest sun is over 100,000 lux.
The autos I've grown don't seem to like much light.
That might be due to the extended light schedule that we use.
I've just switched this grow from 20-4 to 18-6 because the lights are so strong.

Lux from the sun starts and ends at zero at sunrise and sunset.
If noon is 100,000 lux, then the average sunlight lux is about 50,000 but at various different angles.
30,000 lux that's constant and has a constant angle for 18-24 hours might be too much.
For me, far away lights at high power work best. I rarely get closer than 30 inches.

 

[Animatey]

I've been getting light burn from about 30,000 lux.
If I get the COBs closer than 30 inches, I get plant stress.
The brightest sun is over 100,000 lux.
The autos I've grown don't seem to like much light.
That might be due to the extended light schedule that we use.
I've just switched this grow from 20-4 to 18-6 because the lights are so strong.

Lux from the sun starts and ends at zero at sunrise and sunset.
If noon is 100,000 lux, then the average sunlight lux is about 50,000 but at various different angles.
30,000 lux that's constant and has a constant angle for 18-24 hours might be too much.
For me, far away lights at high power work best. I rarely get closer than 30 inches.

Thanks for the numbers bro! I'm also not sure why they can't take much light compared to the sun but I think you're on the right track.

Autos definitely can't take as much... I had photos over 80k that did fine and finished strong under same exact cobs. I didn't want 80k but she kept stretching and I ran out of space. I think 45k or is less good for 12/12 with photos.

I agree with the idea night hours will help.

I usually go 24/0 but switched to 20/4 and will probably go 18/6 once stretch is done.

I'm doing a different form of hydro (top feed recirculating) where I can get away with higher rez temps and not get root disease, but I think the higher rez temps (77f) were like drinking hot water and probably made the light stress worse. Got the temps down today so I'm going to see if that was part of the problem.

 

[Olderfart]

For me, far away lights at high power work best. I rarely get closer than 30 inches.

Interesting that you mention this - my sentiments exactly, but more according to theory than my very limited growing experience. Light from afar is better for "penetration" because the intensity will vary less through the depth of the canopy. One of the reasons that sunshine is as effective as it is.

Good on you for mentioning this.

 

[Arthur]

Does it look like this?

Running 450w of cobs.

If adjust to the average canopy level, I seem to always get 1 or 2 that get a bit too tall and bleach.
Average distance is 24" and this one has jumped to 17" under 3500k.

Over the runs, at least for me, I'd rather have a little damage on 5% and max out the rest.

But on a nice flat deck, I'll bring the lights in till I just start seeing some scorching, and then back off a little.
Probably 85% of the autos I've run are happy at about 24" some griped with 30" and others will let me get into the mid teens.

 

[Animatey]

Does it look like this?

Running 450w of cobs.

If adjust to the average canopy level, I seem to always get 1 or 2 that get a bit too tall and bleach.
Average distance is 24" and this one has jumped to 17" under 3500k.

Over the runs, at least for me, I'd rather have a little damage on 5% and max out the rest.

But on a nice flat deck, I'll bring the lights in till I just start seeing some scorching, and then back off a little.
Probably 85% of the autos I've run are happy at about 24" some griped with 30" and others will let me get into the mid teens.
View attachment 1137343

Looks similar, but it's just started so it almost looks like Mg def. Also the serrated leaf edges are slightly curled and burned looking almost like heat stress.

I thought it was Mg def except none of the lower growth had the issue so eventually after a full day of troubleshooting, some ppl here helped me figure out it was light stress.

I think the big issue was that I lost control of my rez temps and they were at 77f...

My guess is that drinking hot water was giving her trouble with the light (and probably other things).

Rez temps are back to 70f and I'm raising the light intensity by 1-2k lux a day and she seems ok now. pH is stable again and so is EC which were both previously requiring me to make twice daily adjustments.

I'm not sure how high I can go with the lux but I'll try to update here as she goes into full flower over the next few weeks.

Thanks for posting some info here on your heights etc. Good knowledge for cob users!

PS here is a pic from a few days ago

Only on the upper most leaves closest to the light

 

[Arthur]

Been a while since I've run hydro, but that temp made me go !