Light Intensity; LED vs HID

MrTwist1 said:

Haha that's actually a really good question! I'll be honest and say that I cannot prove it to matter, although it does seem to be the common consensus.

Basically I believe that photosynthesis works more efficiently when the separate chloroplasts each receive a full spectrum of light. That is to say, I do not believe that, even if separate chloroplasts can act cooperatively to accumulate different frequencies of light to then be summed within the plant... that it would be as efficient as a full spectrum of light covering each and every chloroplast.

I am ready to be corrected if anyone can shine further light on this (pun intended).

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As much as I wish this thread dead I think you're right. If your thinking that it would be better to have mixed light covering the plant as opposed to say red blue and white LEDs on 3 areas of the plant. Simply because the plants leaf is using the light to make energy in itself. If you had 1 leaf with only blue 1 with only red and 1 with only white then the plant would very likely not be happy.

MrTwist1 said:

Haha that's actually a really good question! I'll be honest and say that I cannot prove it to matter, although it does seem to be the common consensus.

Basically I believe that photosynthesis works more efficiently when the separate chloroplasts each receive a full spectrum of light. That is to say, I do not believe that, even if separate chloroplasts can act cooperatively to accumulate different frequencies of light to then be summed within the plant... that it would be as efficient as a full spectrum of light covering each and every chloroplast.

I am ready to be corrected if anyone can shine further light on this (pun intended).

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Ive seen the mixing recommendation in other posts but I've also seen folks using blurples really close to canopy and growing decent flowers.

I was only curious. My lights are as high as i can get em.

testiclees said:

Ive seen the mixing recommendation in other posts but I've also seen folks using blurples really close to canopy and growing decent flowers.

I was only curious. My lights are as high as i can get em.

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The proof is in the pudding, as they say... although maybe "in the pipe" would be more fitting

You can only drop your light until the point of highest intensity damages your plants.

If you have one high power source over your canopy (HID or a highpower cob), you have really high intensity in the middle of your beam that is limiting how low you can drop your light and its giving the edges the shaft. (Somewhat mitigated by a quality reflector)

If you have 16 low(er) power points of light (say 35w a piece) then you are only limited by the highest intensity in the middle of one of those beams. You can drop your light a lot lower when the highest concentration of photons is coming from the center of a 35w emitter rather than a 1000w emitter.

Prefab units are not clustered together in a box because that is a good design for light distribution. Its just easier to build/ship a luminaire that way. The best designs have as many diodes as you can afford, driven as softly as you can afford, spread out as evenly over the canopy as you can logistically manage.

akdrum said:

I would like to know something about distance and discreet diode spacing in relation to how close you can hang lights to the canopy. If you have a light that is say 500w and you hang it 3 ft above the canopy to get a specific spread of the light, say a 4' x4' coverage, and you have an average PPFD of some given # at that height, could you take those same diodes and spread them over say a 4' x 4' space and lowered them to say about 6" over the canopy, use no reflectors, would/could you achieve the same PPFD but have a more uniform coverage of the space. Light density decreases with distance so is there an advantage to moving in close? Is this a good idea to pursue for a build? I have not found any reference about this. Any thoughts?

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akdrum said:

I would like to know something about distance and discreet diode spacing in relation to how close you can hang lights to the canopy. If you have a light that is say 500w and you hang it 3 ft above the canopy to get a specific spread of the light, say a 4' x4' coverage, and you have an average PPFD of some given # at that height, could you take those same diodes and spread them over say a 4' x 4' space and lowered them to say about 6" over the canopy, use no reflectors, would/could you achieve the same PPFD but have a more uniform coverage of the space. Light density decreases with distance so is there an advantage to moving in close? Is this a good idea to pursue for a build? I have not found any reference about this. Any thoughts?

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I think there's huge advantage to close growing. I do w/ my vented HPS. There's no footprint there. Hoods all right close to each other. Ceiling of light.
Fluence is close growing. But it's only good for one style of growing really. Even scrog!

I believe that if the source of light is more intense then the decrease in PPFD drop over distance will decrease. (Whe were referring to the drop being more then HPS under the canopy) Allowing for more total density/intensity below the canopy. Which fits all styles. So you could grow tall plants too. HO single sources/LES/cob whatever.
Often time Ceiling height is required, lenses do the trick to but you'd want your light to cross so they'd have to be close enough.
But really, don't mind me. I'm hypothesizing & am not a DIY'r.
I do though have experience with close growing & tall as well as the light sources needed to do both.

Transmittance(I.E. penetration) doesn't care about the distance to the source. It will absorb, reflect, and transmit the same no matter how far away the light is coming from. All it cares about is the light on the top layer of canopy.
Then to take it further...a single point source spreading is going to have more reflection via lower incident angle and thus having less transmittance on the canopy as a whole than many spread source(s) with more perpendicular incident angle to the canopy
While spreading the sources you are not only limiting reflectance but also increasing "penetration" by diffusion to increasing tissue exposure rather than relying on light spill from a single source.

If you don't agree...please write a personal letter to every plant physiologist and professor to fuck off...as well as submit a full study to a scientific journal so they can all learn from you.

End of story

Don't you people ever get tired of of spewing all this negativity. There are also advantages of multiple lights sources and not everyone is trying to grow trees indoors. With my setup of one COB per sq/ft I can invest extra time and scrog a single plant for max yield (20 oz's) or just put a small plant in and let it go natural (no training) and end up with a 3.5' to 4' tall plant (12 oz's) with solid buds all the way to the bottom,no fluff. This with about 740 PPFD,if I needed to grow something taller all I would need to do is crank up the PPFD. Multiple sources from COBs have the advantage of unreflected light coming from different angles to go deeper into a plant without having to pass through leaves. You know there are disadvantages to growing trees,longer veg times and less crop cycles per year,more plant maintenance to keep them open enough for light to get in so you don't end up with lots of fluff and harder to work on. Not everything is only black or white,most things are grey and if your happy with HPS knock yourself out,there's more than one way to skin a cat,just a old saying and not bait for our favorite HPS champion. And all this fighting and name calling about the perfect spectrum is BS too,the difference between quality and yield of 2700k to 4000k in flower is not that huge so just let it go,some people go for yield and some quality is more important and some go for the middle.

ok! Sounds good! Advantages to both.

Hybridway said:

I believe that if the source of light is more intense then the decrease in PPFD drop over distance will decrease.

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that statement is false.

Ok fellas, let's paint the scene:
10'x10'x20'deep box.

Scenario 1: Assuming a 100W Hps has the same lumen per watt efficiency as a 1000W we hang 10 100W fixtures with nice reflectors on the ceiling.

Scenario 2: single 1000W hps with nice reflector is hung on the ceiling

Center par reading is taken on the floor 20' down - which has a higher par reading?

OneHitDone said:

Ok fellas, let's paint the scene:
10'x10'x20'deep box.

Scenario 1: Assuming a 100W Hps has the same lumen per watt efficiency as a 1000W we hang 10 100W fixtures with nice reflectors on the ceiling.

Scenario 2: single 1000W hps with nice reflector is hung on the ceiling

Center par reading is taken on the floor 20' down - which has a higher par reading?

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should be almost the same. but what is the relevance? very few growers have 20' ceilings.

PurpleBuz said:

should be almost the same. but what is the relevance? very few growers have 20' ceilings.

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I would be very interested in the results of such test.
It just exaggerates the comparison between single point and multi point at the same wattage

OneHitDone said:

I would be very interested in the results of such test.
It just exaggerates the comparison between single point and multi point at the same wattage

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just look at the sun. if you elevate a single point enough it becomes a large uniform point. just like the sun

The debate over indoor lighting systems is still asinine. Try beating our solar system's sun. The whole debate is like debating over the two sides of the same coin.

Rayne said:

The debate over indoor lighting systems is still asinine. Try beating our solar system's sun. The whole debate is like debating over the two sides of the same coin.

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sounds like the only thing asinine is your statement. why are you trolling ?

Snagged this from an aquarium lighting article (linked below), apparently I'm not the only one thinking along these lines
I'm sure @Hybridway would agree

Intensity

When we talk about intensity, generally we're not referring to Watts
- this is a measurement of power consumption, and not output.

An obvious example is a 40W incandescent light bulb compared to a 40W fluorescent (FL) tube.
The tube is VERY much brighter. Similarly, a 36W PL-L 6500K tube is also much more intense than a 36W FL tube.

The intensity of a bulb is directly related to the depth of water the light can penetrate.
For instance, a 400W MH (metal halide) bulb puts out about the same intensity as 10 X 40W FL tubes.
However, because MH light is a point-source light, ALL the intensity is concentrated at one point
and this is why it can penetrate down to at least 30" easily, whereas 40W FLs only go down to about 12" effectively.

Adding 10 FLs does NOT make any difference. You just get a much wider spread,
but the penetration is still 12" per tube, just over a wider area only.


In the past, a favourite form of measurement used to be watts/US gallon, and ranged from 5-10 W/G of white light for reef tanks.
Because reef tanks could be very odd-sized, some tall, some short, this wasn't very practical,
and nowadays more people are starting to use W/sq.ft. of surface area,
lying between 50 - 150W / sq.ft. of white light, depending on the corals you plan to keep.


Note on effective water penetration power of bulbs and tubes :
Fluorescents - down to 12"
CF like PL-L, T4 and T5 - to 15"
MH 70W to 16"
MH 150W to 20"
MH 250W to 24"
MH 400W to 30"

http://www.fishyou.com/saltwater/sw-light.html

PurpleBuz said:

that statement is false.

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It showed that to be true earlier in this very thread. W/ the SK, Illumitex, & HPS. The drop was much less.
@OneHitDone explains it using the fish tank in water. Same concept. (Good ex.)
But I am in no way coming back to this thread to argue or even participate any further. Just answering a question that was quoted to me.

I would be curious on how they measured this. Is it a single sensor directly under the 400 HPS,hot spot? The link reads like one mans opinion and not anything scientific.

OneHitDone said:

Scenario 1: Assuming a 100W Hps has the same lumen per watt efficiency as a 1000W we hang 10 100W fixtures with nice reflectors on the ceiling.

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Problem is that a 100W HPS doesn't come close to the efficiency of a 1000W HPS. Especially not to a double ended HPS.

A 100W HPS gets about 1.4umol/s/W from the bulb and a proper 1000W HPS produces 2.1umol/s/W from the bulb.

OneHitDone said:

The intensity of a bulb is directly related to the depth of water the light can penetrate.
For instance, a 400W MH (metal halide) bulb puts out about the same intensity as 10 X 40W FL tubes.
However, because MH light is a point-source light, ALL the intensity is concentrated at one point
and this is why it can penetrate down to at least 30" easily, whereas 40W FLs only go down to about 12" effectively.

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That is not true either

You get overlap from those 10 FL's and with that you will get roughly the same "penetration". It's not identical since the light is spread out better, but in the middle the HID will win and around the edges the 10 FL's will win. On average you will see the same "penetration".