Help me understand something

I know the lower wattage you run a cob the more efficient it becomes. But is the intensity of the light a factor as well? If I ran two cobs at 20 watts and a single cob at 40 watts, won't the intensity and penetration be better on the 40 watt than running 2 cobs at 20 watts each? If I take a flashlight and it has a 100 watt bulb, it will shines nice and far and bright and then I take a flashlight with 100 1 watt bulbs will I get equal distance/visibility/penetration?

In my head it seems like one at higher wattage will penetrate/travel farther than many at a lower wattage each.

You are right. Just like the sun being so intense. Download a lux meter app for your cell phone, take two readings outside one at the ground and one at shulder level. You should see very little difference. Now go inside, do the same with any artificial light source. Penetration dosent mean it can go through an opaque surface though, you need distribution in addition to intensity, so your confusion is understandable.

The reason lower wattage is better is due to lower heat created by the power; amps/watts; and more u/moles per watt the plant can use. The lower wattage penetrates further because it is more energy than the more intense light due to efficiency the led of light at lower temperatures. Perception is not always reality. Most light our eyes can not see, like UV, IR 380nm - 450nm, sunstroke, heat rash, sunburn, Black lights,etc. 450nm - 830nm is Green, Blue, and Yellow.

Penetration is a function of u/moles. Higher u/moles are associated with higher efficiency and longer light travel. The led transforms power; amps/volts; into u/moles at the highest level creating the most penetrating light available from that led. Example a cree 3590, 36v will be more efficient at 25w/700mA than 50w/1400mA. The lower amps will grow better than the the same at 50w with more energy intensity light and less heat energy. That is why the Samsung chip works so well, it is efficient in electrical energy transformation into light energy for plant photosynthesis.

Another factor is light spectrum that also determines growth. Another subject altogether.

VegasWinner said:

The lower wattage penetrates further because it is more energy than the more intense light due to efficiency the led of light at lower temperatures...Penetration is a function of u/moles. Higher u/moles are associated with higher efficiency and longer light travel...The lower amps will grow better than the the same at 50w with more energy intensity light and less heat energy.

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These are exactly the answers I've been looking for.

I'm using a Citizen 1212 5000k in a 4 sq ft space for vegging clones and seedling. The light is about 26 inches away from the plants. Visually they are getting plenty of light but I always wondered if the lack of intensity could be responsible for the perceived slow growth compared to the T5s and CFLs I used in the past. There is no stretching and the stems are thick just as what being describe with using the 5000k spectrum. But growth just seem slow, and the plants from seed at this point are light green in color showing some form of deficiency. Could this be a sign that the plants need more nitrogen and or magnesium, because of the spectrum AND lack of intensity? Pic isn't the best, but you can see the color on the plants from seed.

"penetration" is a fuzzy term, meant for porno.......that reminds me I need to pay my xfinity bill asap

ChefKimbo said:

These are exactly the answers I've been looking for.

I'm using a Citizen 1212 5000k in a 4 sq ft space for vegging clones and seedling. The light is about 26 inches away from the plants. Visually they are getting plenty of light but I always wondered if the lack of intensity could be responsible for the perceived slow growth compared to the T5s and CFLs I used in the past. There is no stretching and the stems are thick just as what being describe with using the 5000k spectrum. But growth just seem slow, and the plants from seed at this point are light green in color showing some form of deficiency. Could this be a sign that the plants need more nitrogen and or magnesium, because of the spectrum AND lack of intensity? Pic isn't the best, but you can see the color on the plants from seed.View attachment 3921376

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you're overwatering and drop your light closer grower.............next time add more aeration(perlite/ricehulls/etc.) to the soil mix too

good luck

PSUAGRO. said:

"penetration" is a fuzzy term, meant for porno.......that reminds me I need to pay my xfinity bill asap




you're overwatering and drop your light closer grower.............next time add more aeration(perlite/ricehulls/etc.) to the soil mix too

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Thank you @PSUAGRO. Out of curiosity, how could you tell that I am over-watering outside of the ugly looking clones?

ChefKimbo said:

Thank you @PSUAGRO. Out of curiosity, how could you tell that I am over-watering outside of the ugly looking clones?

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not hard to see from the pics that the soil is saturated with poor drainage imo, use a finger to "penetrate" the soil,lol /lift pots/or buy a cheap moisture probe to follow good watering habits.

ChefKimbo said:

These are exactly the answers I've been looking for.

I'm using a Citizen 1212 5000k in a 4 sq ft space for vegging clones and seedling. The light is about 26 inches away from the plants. Visually they are getting plenty of light but I always wondered if the lack of intensity could be responsible for the perceived slow growth compared to the T5s and CFLs I used in the past. There is no stretching and the stems are thick just as what being describe with using the 5000k spectrum. But growth just seem slow, and the plants from seed at this point are light green in color showing some form of deficiency. Could this be a sign that the plants need more nitrogen and or magnesium, because of the spectrum AND lack of intensity? Pic isn't the best, but you can see the color on the plants from seed.View attachment 3921376

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Turn that COB down and add more u/moles. The reason the leaves are light green they are not getting enough chloroplast from light energy. ytes you have a bright light just not a lot of energy in it. Since you have low energy you are overcompensating with feeding schedule. I would ad more light energy. maybe add a second CLU to the mix and run them half as had and you might be a lot happier. For veg I run cree cobs at 12-15w and get fantastic growth no stretch and bushy. I have been using additional royal blue cree xpe-3w leds but recently changed out the royal blue for a 30w full spectrum running at about 15w I figure and the plants love it. Lower is better when it comes to cobs, All cobs. Many folks like to drive teir cobs hard it looks bright, but that is the opposite you want to do, as you are experiencing. T5's running lower wattage does better than a CLU running higher wattage.

ChefKimbo said:

Thank you @PSUAGRO. Out of curiosity, how could you tell that I am over-watering outside of the ugly looking clones?

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your leaves are droopy. Happy plants have leaves pointing up to the light, not down.

VegasWinner said:

Turn that COB down and add more u/moles. The reason the leaves are light green they are not getting enough chloroplast from light energy. ytes you have a bright light just not a lot of energy in it. Since you have low energy you are overcompensating with feeding schedule. I would ad more light energy. maybe add a second CLU to the mix and run them half as had and you might be a lot happier. For veg I run cree cobs at 12-15w and get fantastic growth no stretch and bushy. I have been using additional royal blue cree xpe-3w leds but recently changed out the royal blue for a 30w full spectrum running at about 15w I figure and the plants love it. Lower is better when it comes to cobs, All cobs. Many folks like to drive teir cobs hard it looks bright, but that is the opposite you want to do, as you are experiencing. T5's running lower wattage does better than a CLU running higher wattage.

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Thanks a ton. Just as I suspected but I just couldn't put it all together. By light energy, you mean more wattage in a sense. The plants need more energy and not just good quality light. I'm running the light on a salvaged Mars driver running at 650ma, like 23 watts I believe. I will be adding another COB to the mix, in the meantime I have some 42 watt cfls begging to get some use. Yesterday I put 4 of the clones under 3 T5s in another area, so i'm going to be taking notes to see what the plants like better.
Thanks again.

linky said:

I know the lower wattage you run a cob the more efficient it becomes. But is the intensity of the light a factor as well? If I ran two cobs at 20 watts and a single cob at 40 watts, won't the intensity and penetration be better on the 40 watt than running 2 cobs at 20 watts each? If I take a flashlight and it has a 100 watt bulb, it will shines nice and far and bright and then I take a flashlight with 100 1 watt bulbs will I get equal distance/visibility/penetration?

In my head it seems like one at higher wattage will penetrate/travel farther than many at a lower wattage each.

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"Penetration" is not simply a function of initial intensity. Focusing via reflectors and/or lenses can greatly increase penetration. A well focused light of moderate intensity will penetrate better than a much brighter light that is unfocused.

linky said:

If I take a flashlight and it has a 100 watt bulb, it will shines nice and far and bright and then I take a flashlight with 100 1 watt bulbs will I get equal distance/visibility/penetration?
.

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Yes, you actually will, IF they are focused into the same beam spread.

penetration is 100% independent of light source. more a function of geometry. a focused light with a reflector can penetrate but will be super intense right below it, possibly too much

best penetration (assuming your canopy isnt so dense it blocks out all the light to the lower part of the canopy) is achieved with a light as far away from the canopy as possible, achieving the proper ppfd at the top of canopy. the ratio of the (distance from light to top of canopy) to (distance from light source to bottom of canopy) is minimized and light is uniform and in the acceptable range lower down into the canopy.

example:
sun
1000 ppfd at top of canopy
999.99999999999999999999999999999999999999999999999999999999999999999999999999999999999 ppfd at bottom of canopy (say 18")

HPS 4 foot above canopy:
1000 ppfd at top of canopy
600-700 ppfd 18" below canopy

T5/quantums/cobs run soft 6" from canopy
1000 ppfd at top of canopy
200 ppfd 18" below canopy

CobKits said:

penetration is 100% independent of light source. more a function of geometry. a focused light with a reflector can penetrate but will be super intense right below it, possibly too much

best penetration (assuming your canopy isnt so dense it blocks out all the light to the lower part of the canopy) is achieved with a light as far away from the canopy as possible, achieving the proper ppfd at the top of canopy. the ratio of the (distance from light to top of canopy) to (distance from light source to bottom of canopy) is minimized and light is uniform and in the acceptable range lower down into the canopy.

example:
sun
1000 ppfd at top of canopy
999.99999999999999999999999999999999999999999999999999999999999999999999999999999999999 ppfd at bottom of canopy (say 18")

HPS 4 foot above canopy:
1000 ppfd at top of canopy
600-700 ppfd 18" below canopy

T5/quantums/cobs run soft 6" from canopy
1000 ppfd at top of canopy
200 ppfd 18" below canopy

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So my 1000 watt vero 29 fixture 24" above canopy (10 at 100 watts each) gives better penetration then my 750 watt 3590 fixtures (12 at 62.5 watts each) 16" above canopy probably? It may not be as efficient running at 100 watts each but being able to keep it higher above the canopy sure gives it great penetration.

linky said:

So my 1000 watt vero 29 fixture 24" above canopy (10 at 100 watts each) gives better penetration then my 750 watt 3590 fixtures (12 at 62.5 watts each) 16" above canopy probably? It may not be as efficient running at 100 watts each but being able to keep it higher above the canopy sure gives it great penetration.

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It depends on the geometry of the fixture's reflector and/or lens assemblies. If the two lights have similar beam spread, then the brighter one will have better penetration, assuming each is raised to a height that results in the same intensity at the canopy.

linky said:

So my 1000 watt vero 29 fixture 24" above canopy (10 at 100 watts each) gives better penetration then my 750 watt 3590 fixtures (12 at 62.5 watts each) 16" above canopy probably? It may not be as efficient running at 100 watts each but being able to keep it higher above the canopy sure gives it great penetration.

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like higgs said, if they are the same in terms of reflectors/lenses/no optics, if they are both delivering the same ppfd at canopy level, the source that is farther will penetrate more consistently

tent reflectance/canopy density/etc buggers this simple assumption up of course, but its a good rule of thumb

pretty much the ideal situation is a dense array, like 1 cob per square foot or more, in a 4x8 tent or greater, hung high as its super uniform and also "penetraing" the canopy from all directions - less shading and the light that reaches the bottom is additive

CobKits said:

like higgs said, if they are the same in terms of reflectors/lenses/no optics, if they are both delivering the same ppfd at canopy level, the source that is farther will penetrate more consistently

tent reflectance/canopy density/etc buggers this simple assumption up of course, but its a good rule of thumb

pretty much the ideal situation is a dense array, like 1 cob per square foot or more, in a 4x8 tent or greater, hung high as its super uniform and also "penetraing" the canopy from all directions - less shading and the light that reaches the bottom is additive

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My "Ideal Light" (for a 4x4) would be horrendously expensive - an array of 144 smaller 30W COBs (like Vero 13's) running at 6W or so, spaced four inches apart covering the entire canopy with 15 degree optics to maximize penetration below the canopy. It would be insanely expensive to build, but man what a light!