Same strain may do diferentially depending of the irradiance used. At low irradiances, spectrums with dominant red, some blue and only a little of other wl does very good (but some strains dont go fine into bloom this way). While at high irradiances, trend is very different, with spectrums with a good percentage of white LEDs (thus more green-yellow) does same or better. Never worse.
This fact has convinced me of the need of using a good number of white LEDs if wanting to have a LED lamp able to bloom in a variety of conditions. Its possible to use little white (and none!) on some conditions/strains, but in general it not work fine on a variety of conditions.
When I say white LED you can put perfectly any other broadband white light source, as fluorescents. Ive been unable to find any noticiable difference between results using white LEDs or fluorescents when percentage of white is similar.
I tend to use more white each day I check results using it or not. On some conditions is possible to obtain a better spectral efficiency using less white, but in general, more white means a guarantee of good results.
So, what are the benefits of narrow optics (beam angle) and wide ones?
Narrow optic:
Pros:
-Lower light losses (less light goes to side walls)
-Light more focused, being able to send more light through a hole in canopy of a given size
-Work very well when placed at some distance of plants (typically, more than 1ft)
Cons:
-More uneven lighting. In the case of using LEDs separated to the next instead of crowded panels, difficulties mixing light spectrum.
-Dont work fine at short distances. Need some distance to get light distributed evenly, and, more as narrower optics used, exist the risk of excessive local irradiances when plants are too close. But in general, they can be used at short distances without deleterious effects, apart of reduced efficacy.
-Shadowing may be an issue.
In general, narrow optics is a good idea when k and/or LAI are low (low k:leaves mostly in angle, not horizontal; low LAI: leaves not too abundant, there is enough holes in the canopy) as it allows to use just top lighting.
So light losses are lower (good), but lighting obtained, less even (bad).
Wide optics:
Pros:
-Very even lighting with excelent spectrum mix still at short distances. Increased efficacy of the light, especially at short distance of the lamp.
-Produces a kind of diffuse lighting: light comes from almost all directions, being able to enter any hole in the canopy, independent of leave's angle
-Shadowing is never a problem.
Cons:
-More light loss due more photons goes to the side walls. Worse as larger is the distance from lamp to plants and walls less reflective.
So this option only have a drawback, but its an important one. I choosed to go this way and use very reflective walls to overcome the problem, as apart of it, IMHO, wide optics are way more versatile. I tend to use side lighting always that is possible, and for side lighting for sure that narrow optics arnt a good idea.
Wide beam angles are very useful on side lighting and where k is high, as there is little shadowing and light enters for all the holes in the canopy, "looking" for them on a 3D fashion, and not by brute force vertically. Two leaves separated 1" vertically may block fully space looking from top, but have a wide hole between them. Wide optics works better here.
But I admit than 90º beam angles are generally enough to get the advantages of "wide optics". I use larger ones simply because LEDs I like for efficiency/price arnt avalaible on it. If I could get good LEDs with 90º optics, I would use them. Using secondary lens on larger beam angle LEDs is not a good solution because they have their own losses.
My ideal LED setup would use 90-120º beam angles on the center, and 30-45º ones on the edges, in order to get the lowest light losses but the more even lighting and more diffuse light. And with LEDs distributed along all the grow area, not all in a central panel.
On the other hand, on side lighting, 120-170º beam angles are ideal. The wider the better in this case.
I am working with optical films, that may overcome all the cons for a relativelly low cost in light. Just changing the curvature of the film, it is possible to get a very wide beam angle and a colimated column of light with high intensity from the same LED string.
The debate between brick panels and LEDs evenly distributed along all the grow area is very similar to narrow/wide optics, but both pros and cons are very extreme. While narrow optics on LEDs result on a more uneven light distribution a short distance, if LEDs are not together in the top center of the grow area, at 1ft from the lamp or less there is already an even lighting. But when all LEDs are in the center, it happen very similar to HIDs, that need relatively long distance to lit effectively all the space, and always producing a very uneven lighting that seriosly drop efficacy of the light.
Using multiples sources of light is all advantages, both if considered for single LEDs or full panels: better 2 panels of 50W instead of 1 of 100, and 4 of 25 better than 2 of 50. There is disminishing results here, past a number of light sources there is little gain, but from 1 to 2 or 4, there is a very noticiable difference. Light distribution is always way evenly this way, and evenly lighting result on increased efficacy. On the other hand below a brick panel penetration is increased because intensity is higher, but it only happen below the lamp, while at the sides, penetration is lower, because the light intensity does.
If you want to work with LEDs but you only want to work with an overhead lamp, then you will have limited penetration. In this scenario, using lenses to achieve narrow beams makes sense in order to get increased penetration. On the other hand, this scenario will obligue to install a high density of watts on the overhead lamp, demanding a way better cooling setup. I think that if you want to work just with an overhead lamp, the best is to use a HID. So I do not advice to use any lenses, but the opposite: wider beam angles.
Lenses arnt esential at all, while they block some percentage of the light emitted. 8-20%. Most lenses blocks about 10-15% of the light. On other application (for human) they are required, but not in ours.
-First factor is related just to photosynthesis itself. It is a matter of fact that photosynthesis driven by red light is extremely efficient at low irradiances (never forget that both McCree and Inada studies were performed under not saturating conditions), but that efficiency drops severely as irradiance increase. Blue efficacy, on the other hand, saturates at higher irradiance. While green-amber can reach nice efficacies along a very wide range of irradiance.
This result on the very high efficacy of green-yellow-amber rich spectrums when high irradiance is used, as required by cannabis to flower fine and grow large buds. I strongly disagree statements about the low efficacy of HPSs, for example. Light from HPS is not wasted, as many thinks by looking at chlorophills absorbance or (better) photosynthesis graphs, as Inada-McCree, because they dont tell the full history.
So up to irradiance used in veg, about half than used in bloom, we can use just red and blue. From that up, we need to add at least as many green-yellow-amber as red and blue together. The best way to add it is by using whites, especially those richest on these wavebands (usually neutral whites, 4000-5000K).
Oh,I really love that lad...a)We can't use just 660nm for flowering. Some strains do accept it, some dont.
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b)Probably we can use larger percentages of blue. At high irradiances, it shouldnt result on a too reduced photosynthesis efficacy, and have some interesting side effects (over terpenes and cannabinoids production).
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c)Some far red is necessary, but often very little is enough.
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Another thing related is the problem of LED growing with low temps. This needs solution, but solving it by heating plants with IR lighting is wasteful. Increase PAR irradiance (especially on the blue range) is a way to increase temperature inside leaves.
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d ) For regulation purposes, cannabis need some of other wavelengths, mainly yellow-amber. This is accomplished by adding white LEDs, but too adding amber (of as shorter wavelength as possible)
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Oh com'on...Me too. dates of these posts would be helpful.
Did not read through the repost, so... I saw him post (~ 1-2 years ago) that one can grow with whites only, and that was way before most recent offerings
Well..( allow me to be the usual @ssh0l# ...)..edit: your girl looks great........interested to see how she finishes
cool toolFound this today. Build Your Own LED on line using their software
can u provide link to purchase these lights?Day 55 for the sick lady ....
Under the questionable (?) CHEAP-NO LENS -NO 660 REDS- 1 WATT leds....
And with a poisoned plant...
66 Watts of white,crappy asian,onewatters....
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Started 4 regular seeds of unknown various landstrains..
I wanna see ,how wild landstrains ,will do ,under these panels...
Curiosity Grow....
Last night I planted them..
(Had them,before ,for 2 days in glass of water with a bit of Maxicrop...)
Today morning I switced on just one panel,above them..
Went to work... ( N.Y. time 00:00 , 5/10 )
None of them ,above the ground..Watered 'em ,with RO water+Maxicrop ( 10 ml / lt )
When I came back from work....( N.Y . time 09:30 )
All four of them ,above the ground...(the back-right ,is still white & closed...)
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Everything is under constraction and anything can be constractedcan u provide link to purchase these lights?
For sure much denser...SDS how is the density of buds till now?? comparing to hps?
Well,I'm not planning to let the " ruined " WR to go all the way to the finish...Looking great! When do you think is the D-day?
What's the leds' ratio that the panel above the new plants has?