Possible to have too much light?

J

jhfhklsnhfldk

New Member
Plant of the Month
February 2016
Hi All,

May sound like a dumb question but I have read that 3000 lumen/sq ft is optimal and above that, CO2 is required. So I first wanted to find out if this is true, and also to find out if 5600 lumen/sqft is too much.

I have a 7.5sqft space with about 42,400 lumen in multiple spectrums, 6500K, 5000k, 3000K, 2700K. This is a combination of cfl and fluoro tubes and is mostly 6500K.

My Temp holds steady at about 77 degrees and humidity is a bit low at 40-45%. I am working on raising the RH.

I have 4 CKS autofems in smart pots that have not broken soil yet. I am using FFOF.

Thanks
Schtiggy
 
Schtiggy said:
Hi All,

May sound like a dumb question but I have read that 3000 lumen/sq ft is optimal and above that, CO2 is required. So I first wanted to find out if this is true, and also to find out if 5600 lumen/sqft is too much.

I have a 7.5sqft space with about 42,400 lumen in multiple spectrums, 6500K, 5000k, 3000K, 2700K. This is a combination of cfl and fluoro tubes and is mostly 6500K.

My Temp holds steady at about 77 degrees and humidity is a bit low at 40-45%. I am working on raising the RH.

I have 4 CKS autofems in smart pots that have not broken soil yet. I am using FFOF.

Thanks
Schtiggy
Click to expand...

Yes you can have too much light... Its called the light saturation point.

I don't measure my light in lumens as it really doesn't have a translation to plant processes, and instead I use Micromoles of Par. For cannabis usually after around 1,100 micromoles PPFD, you will see a decline in photosynthesis unless adding extra CO2 and from most of the documentation I have read around 1500 micromoles is the point you will see a decline again in photosythesis and between 1500-2000 micromoles is typically the light saturation point of cannabis.

I'm not sure what that would be in lumens since you can't really take Lumens to micromoles in conversion but to answer your question, yes, your plants can have too much light.
 
[HELP} Question about led lights. I use t5 lights for veg with couple of u/v tubes mixed in. Plants look green and great. But when I put plants under my new Leds. The leaves turn yellow and leave green veins in leaf. Lights are 18 in above plants. I just put some cal-mag in 1st week of being in flowering. Any Ideas of what's going on or is this normal for Led's?? Use roots organic dry nutrients which you add once a month to a fox farm potting soil. New led light set up. 900w for 5x5 area. THANKS MY FRIENDS!
 
What fixtures? 3watt/5watt,COBs? watering with ph7.0 H2O? Couldn't hurt to add calmag,Soil Buffers and doesn't draw it like coco. maybe raise the fixtures 4inches and see how they respond
Could need some nitrogen. Are u using Calmagplus? If so I get high% of N also in the Calmag
Can I see pic
U ever try the bottle nutes and ph the solution to 7.0
 
So that means I have 15000 lumen's per square foot and that's bad, how come it does this then
IMG_20151216_225637_1.jpg
IMG_20151216_230844.jpg
IMG_20151216_170822.jpg
cause my plants are always very healthy and very big, thats 1 plant in a 2x2 metre tent and it fills the whole thing, I think that yes you can have to much light........ if you don't know how to use it. If you have extra light you need to do extra home work
 
Nice, I guess what I'm trying to say is, don't go by other people's rules, usually they are rules that are untested, push the limits if u use to much the plant will tell you, not some rule book.
 
Regarding light intensity and spectrum:
~ Would be nice to compare the PPFD of the two different systems to know the intensity. I assume a significant and sudden change in intensity could shock your plants.
~ And, would be nice to compare the two spectrums. Might a significant and sudden spectral shift also shock your plants?

Healthy plants can usually adapt to a relatively wide range of growth variables. If the lighting is an issue, then slowly expose your plants to a new light. Maybe over a week, gradually move the T5 away and bring the LED closer. You may still get some tired leaves, but all of the new growth will be in response to your new light.

Aside:
I'm working with a 250 watt (actual power consumption) four COB LED that produces about 1200 micromoles at 18" on center. Clearly, this is too intense, so I have the light at 24" and it produces about 800 micromoles on center. A rule of thumb that I use... I try to ensure that I can measure between 500 and 900 micromoles at the canopy.

Happy Farming. :)
 
Schtiggy said:
Hi Ice,

Thank you VERY much for the reply, I guess this was not such a dumb question. I will have to do some research to find out how much light it takes to slow the plants growth and when I need to add co2.

Thanks again,
Schtiggy
Click to expand...

From the research I have done, up to around 1,100 micromoles/m2/s-1 is the limitation you want to take your plants without added CO2. After this point there isn't enough CO2 to become fixated within the leaf structures and the extra light is pretty much a waste, and will slow the rate of photosynthesis.

If using CO2, you can take your intensity up to 1500-2000 micromoles/m2/s-1 and at 2000 micromoles (the intensity of the sun at the equator on a clear day) this is the saturation point where photosynthesis becomes disrupted and the rate slows.


So generally if flowering in a 12/12 schedule you want to see

at least 510 micromoles PPFD
optimal is 800-1100 micromoles PPFD without added CO2
800 - 2000 micromoles PPFD if supplementing CO2.

This is only for 12/12 schedules, if using 18/6 or another light regiment, then these numbers change based on the length of daylight.
 
cavanaugh said:
[HELP} Question about led lights. I use t5 lights for veg with couple of u/v tubes mixed in. Plants look green and great. But when I put plants under my new Leds. The leaves turn yellow and leave green veins in leaf. Lights are 18 in above plants. I just put some cal-mag in 1st week of being in flowering. Any Ideas of what's going on or is this normal for Led's?? Use roots organic dry nutrients which you add once a month to a fox farm potting soil. New led light set up. 900w for 5x5 area. THANKS MY FRIENDS!
Click to expand...

Its fairly normal for LED's (blue/red) ones to cause this because of the spectrum. its typically related to a Mg deficiency, and my theory on this is because in each reaction center where photons are processed and carbon fixation takes place, the center of each photosystem protein is a molecule of MG. Since blue/red LED's target the chlorophyll peaks, this increases the rate/metabolism of the plants photosynthesis process by bypassing electron excitation targeting the specific receptors. Because Mg is in the center of each of these "light factories" the plants require more of it than traditional lighting with full spectrum or non targeted spectrum because of the way electrons are brought to excited states and lowered in energy until they reach the reaction centers.
 
Since there is no data, my comments are clearly generalizations punctuated by what I hope are constructive analogies.

Regarding intensity: If that is your experience, then great! You don't have any issues with your lighting. However, it is quite possible that when you switched lights, any difference in intensity was simply not an issue. What happens when you go from 300 micromoles up to 1200 micromoles; ie, "a significant and sudden change in intensity"? Neither you nor I know the intensity; nevertheless, yes you can hurt your plants with lights.
 
Hi Ice,

Some of my research included your YouTube videos. I am in the process of re configuring my grow and have ordered LED lights based, in part, on your video showing the DS XTE 300 light levels at various distance. I am still working on it, the knowledge base that is, and expect that it will be quite a while before I have the science down to an art.

If I could ask, what is the meter you are using called? Is it simply a "light meter"? I would love to be able to gauge as you do in the video.

Thanks again.
 
Schtiggy said:
Hi Ice,

Some of my research included your YouTube videos. I am in the process of re configuring my grow and have ordered LED lights based, in part, on your video showing the DS XTE 300 light levels at various distance. I am still working on it, the knowledge base that is, and expect that it will be quite a while before I have the science down to an art.

If I could ask, what is the meter you are using called? Is it simply a "light meter"? I would love to be able to gauge as you do in the video.

Thanks again.
Click to expand...

The meter in the video I am using is called in general terms a "PAR meter" or by specific name called a Quantum Meter. The meter measures the "amount of photons" that a light puts out every single second, and the unit of measurement is micromoles/meter squared/per second. Another name for this type of measurement is PPFD or Photosynthetic Photon Flux Density.

The meter I am using is a Apogee MQ200 which retails for around $380. There are more accurate ones by the brand Li-Cor which retail upwards of $1,000+ but are much more acceptable for even more accurate measurements. My meter, the Apogee can have about a 10% error range depending on the light source, color and type being measured.

The most accurate way to measure is with a spectroradiometer, which measures light in tiny bands which are split by a diffraction grading, but the cheapest spectroradiometers are around $1500 and can go up to around $40,000.

For those XTE panels, the datasheets can be found at the website for advanced, just go to their main website and add to the URL after the dot com "/datasheets/ and hit enter.
 
doctor green said:
Sorry mate but your assumption is wrong the only shock I saw was an extreme level of growth at a rate that is unbelievable , tighter node spacing, tighter than normal for the strain, inreased water uptake.

The only one that was shocked was me it blew all my assumptions out the window
Click to expand...

This, after just saying dont listen to people with rule books. Lol. Dont listen to people period. Find the answers for yourself..

Youve never seen a plant stressed from being introduced to better/more powerful lighting?....i have.

Icemud said:
Just curious but who said 15,000 lumens is bad? the sun puts out approximately 100,000 lumens per square meter at the earth surface, so according to that, you could add a lot more :)
Click to expand...

100,000?! I better go reread, coulda swore i read 10,000 somewhere.

Has no one seen a plant thats been light bleached?
light_bleached.jpg
 
Icemud said:
I'm not quite sure what you are trying to say here?

I think you are not understanding that what I am talking about is Photon count/Micromoles per square meter every second...NOT lumens (or linens).

Lumens are a measurement for people/humans and how we see light, but have no relationship to how plants "see" light. Plants are photon counters, they absorb photons and the electrons from photons are used to split water and carbon dioxide to create ATP and NADP H+. Lumens have nothing to do with plants. Light measurements for plants should be done by Photon count, or PPFD measured in the unit micromoles/meter squared/per second.

Therefore what I was saying is that at MAX, you should be not giving your plants more than 1500-2000 photons PPFD, this has absolutely nothing to do with lumens. Hence the phrase "lumens are for humans, PAR is for plants"

I suggest you visit my current journal as I explain all of these lighting terms in details for anyone to understand, and you will get a better idea of what I am talking about, and how it applies to plants.

As a hint to you, I am very very very researched in plant lighting and typically play the "teacher" role here at 420 magazine when people don't understand plant lighting. Not saying I know it all but I am 100% certain in the information I share is accurate and backed by major research abstracts :)
Click to expand...
I completely understand what your saying and the linen's lol is my phone changing lumens with it's ridiculous auto correct, you can do as much technical "research " as you like, do you understand when I say none of this means anything unless you have actually applied the light in the real world on your plant to find it's own saturation point, different strains take different amounts of light.

I don't mind what terms people use to "measure "light heck it could be footcandles, real world experience will benefit any new grower more than something they have read but not applied.

I'm not saying you are wrong.

I'm saying that all information read, needs to be put into application and tested to gain you any experience, I suggest also that you come and have a look at my journal and my monster of a plant that can easily take 6 x 600 w in a 2x2 m tent and thrive so you know the point I'm trying to make
 
DankWolf907 said:
This, after just saying dont listen to people with rule books. Lol. Dont listen to people period. Find the answers for yourself..

Youve never seen a plant stressed from being introduced to better/more powerful lighting?....i have.



100,000?! I better go reread, coulda swore i read 10,000 somewhere.

Has no one seen a plant thats been light bleached?
light_bleached.jpg
Click to expand...
Yes ofcourse you can light bleach plants, but different strains even different phenos do take less or more light before having to much and light bleaching and I find this point to take the plant to the max.

Sometimes to do better than ordinary you need to enter the danger zone hahaha, just like you said wolf you find the answers for yourself
 

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