LED and BUD QUALITY

[foomar]

Running three cheapo 100 w in a two by four tent drawing 240 ish watts at 80% , all was good in the summer and growing as well as the previous CMH and HPS with same clones.
Get to winter and plants look awfull , stunted and yellowed with brown spots all over.

Leaf temp turned out to be the primary cause , dangling a 125 watt 2700k CFL in place of the central led solved everything.
Took leaf temp from 15 to 25 , below 20 there was little growth or transpiration.

Am happy with this but its nearing the end of its life , are there better sources of the infra red heat and the best wavelength to replace it ?

 

[Rocket Soul]

Running three cheapo 100 w in a two by four tent drawing 240 ish watts at 80% , all was good in the summer and growing as well as the previous CMH and HPS with same clones.
Get to winter and plants look awfull , stunted and yellowed with brown spots all over.

Leaf temp turned out to be the primary cause , dangling a 125 watt 2700k CFL in place of the central led solved everything.
Took leaf temp from 15 to 25 , below 20 there was little growth or transpiration.

Am happy with this but its nearing the end of its life , are there better sources of the infra red heat and the best wavelength to replace it ?

One frequent poster here has tried incandescent bulbs with good looking results
Another would be halogen spots. Or infrared ceramic emitters.

 

[Hammerhead]

T12 used to be what we used for a long time. T5 took their place. Use whatever light you have. You can get decent weed from a fluorescent grow.

 

[CocoNut 420]

I started vegging seeds under 12-12 so it's difficult to say how old or what week but they're roughly 4 weeks since sexing, so say 3 weeks flowering.

I'm getting good results (for me i mean) with 12-12 from seedling but I find the plants can still get to a good size (25/30" ave)
I want more smaller plants so I'm trying 11/13 after sexing.

It's the 1st crop so I can't say for sure what made what difference I need more time to repeat it, the plants are definitely shorter @20" after stretching so it does look promising, it confirms what I seen/heard on YouTube.

I'd say they're slightly ahead in terms of budding in comparison to my other crops done @12-12, again it looks promising but needs repeated.

I enjoy the growing as much as the smoking these days

 

[Ca++]

Where on earth did you get that idea?

I mean, it's in the name!

PPFD = Photosynthetic PHOTON Flux density.

Ie: The density of photons in the 400-700nm range that fall on 1m2 each second

Specifically measured in umol (micromoles) of photons!

EDIT: OK, Rocket beat me to it. At least you now agree with us. Fair enough.

I had about 3 things going on. I'm pretty sure I usually get it right

Something didn't compute, elsewhere in your post. Which I was trying to rationalise. Today I look, and see straight away your 400nm blue photon, isn't blue. So things were not sitting right. You said blue has 50% more energy than red, which was where my head was at. Some of my head on blue, and some on 400nm, trying to see this 50% gain over red, that's orange. My back n forth had me rewriting physics to make sense of it. I still can't, as I fall back on my past understanding. Unable to see the 50%. I mean, yes 600 is 50% more than 400, but to get from 400 to 600 is a 50% gain in wavelength. The energy is inversely proportional. 50% less energy. One is double the other by this route, which I have heard about red and blue before. I'm not sure they got it right though. If we are loosing energy over the spectrum, we have gone from 600 to 400, a 33% difference. I can't make it fit. Planks law governs this, and while I have not used it, I have seen examples. 400nm is about 1.6 uV and blue about 1.8 uV. 700nm is 3.3uv. Our visual spectrum span from one value, to about double that value. Nothing I have ever heard quite gets the difference between red and blue within reason. I must really do the damn maths, but again I feel my brain coming up to simmering lol

I'm doing my high school maths at the moment. However I look at Planks constant and see lots of stuff in a sequence with brackets here n there.

Planck constant - Wikipedia

en.wikipedia.org

I will take my hat off to anyone that can work though that. I'm not sure if you did, or are just looking at other peoples findings?

 

[Prawn Connery]

I had about 3 things going on. I'm pretty sure I usually get it right

Something didn't compute, elsewhere in your post. Which I was trying to rationalise. Today I look, and see straight away your 400nm blue photon, isn't blue. So things were not sitting right. You said blue has 50% more energy than red, which was where my head was at. Some of my head on blue, and some on 400nm, trying to see this 50% gain over red, that's orange. My back n forth had me rewriting physics to make sense of it. I still can't, as I fall back on my past understanding. Unable to see the 50%. I mean, yes 600 is 50% more than 400, but to get from 400 to 600 is a 50% gain in wavelength. The energy is inversely proportional. 50% less energy. One is double the other by this route, which I have heard about red and blue before. I'm not sure they got it right though. If we are loosing energy over the spectrum, we have gone from 600 to 400, a 33% difference. I can't make it fit. Planks law governs this, and while I have not used it, I have seen examples. 400nm is about 1.6 uV and blue about 1.8 uV. 700nm is 3.3uv. Our visual spectrum span from one value, to about double that value. Nothing I have ever heard quite gets the difference between red and blue within reason. I must really do the damn maths, but again I feel my brain coming up to simmering lol

I'm doing my high school maths at the moment. However I look at Planks constant and see lots of stuff in a sequence with brackets here n there.

Planck constant - Wikipedia

en.wikipedia.org

I will take my hat off to anyone that can work though that. I'm not sure if you did, or are just looking at other peoples findings?

The formula you are looking for is:

E = HF

Where "E" is energy, "H" is Plancks Constant and "F" is Frequency/Wavelength

Using this formula . . .

400nm photon = 3.1 ev

600nm photon = 2.066 eV

As you can see, 3 over 2 is 1.5 is 50% more energy. Indeed, using the above formula you can calculate the difference in energy of two wavelengths simply by dividing the larger number by the smaller number (or vice versa). Planck's Constant is, after all. . . . constant!

If we nitpick the "colours", then yes: 400nm is actually violet (or UVA) and 600nm is orange. But I was using the accepted definition of blue = 400-500nm, green = 500-600nm and red = 600-700nm.

In any case, it was a simple example (using simple numbers) of the difference in energy between PAR photons to explain why not all PPFD is the same.

 

[Prawn Connery]

The above formula shows why a a 5000K CRI80 LED – which is heavy in blue and green light – can cause more photo-oxidative damage to plant cells than a 3000K CRI80 LED – which is heavy in red – for the same intensity, or PPFD.

However, it will also depend on the presence and ratio of light-absorbing pigments, as once those pigments are saturated, any photons that are not photosynthesised, reflected or fluoresced will be converted to heat.

Most growers know about Chlorophyll A and B, but there are other pigments that absorb and reflect light that contribute to photosynthesis or photomorphology.

Chlorophyl A

and Caratenoids

 

[Ca++]

When I really look at it, umol isn't a great metric. Quite a few manufacturers have put in extra red than they thought ideal for the plants. Just to get a higher count of these less energy intensive (longer wavelength) photons. Selling us this photon count, rather than the energy emitted.

I thought at some point a scale had come about, that was weighted. I'm a few cans deep again though. It's 7am nearly here.

 

[Crooked8]

Truffle Mintz at 8 weeks, gonna be some seriously fat stacks in here this run. Very happy w the morphology here. I never got buds this huge under HPS. This one smells and tastes like pungent rhubarb and raspberry with a truffle back end. Extremely oily, makes finger tips look like they're soaking wet.

 

[Prawn Connery]

^ OUT-FOCKING-STANDING!

The proof is in the LED. You can't argue with proof.

 

[Prawn Connery]

When I really look at it, umol isn't a great metric. Quite a few manufacturers have put in extra red than they thought ideal for the plants. Just to get a higher count of these less energy intensive (longer wavelength) photons. Selling us this photon count, rather than the energy emitted.

I thought at some point a scale had come about, that was weighted. I'm a few cans deep again though. It's 7am nearly here.

I am guilty of this myself. Those 660nm photons are very efficient to make – somewhere around 4.2-4.4 umol/j for the 3535 LEDs we use. When you combine a few of those with quality white phosphor 5000K CRI70 that are around 3.15 umol/j, you get a very efficient fixture with a higher colour rendering index as a bonus, around CRI90. The resulting spectrum will obviously grow plants. But how well?

On paper, it makes sense. One photon has the same photosynthetic value regardless of wavelength (colour). At least within the PAR range and slightly beyond.

The issue is that each photosynthetic pigment can only synthesise so much light in a given period of time.

My initial thoughts are that because the electron chain is shorter for converting deep red (~660nm) photons to P680 (Photosystem II), they can be synthesised more efficiently and at a greater rate. This would mean that PSII would become saturated at a faster rate and those excess photons would start to photo-oxidise the cells.

In other words, light bleaching. Which is what you sometimes see under very efficient LED fixtures that have a huge 660nm peak.

Blue light, on the other hand, needs a much longer electron chain – that is, a 400nm photon needs to excite a longer chain of electrons to remove enough energy to convert the original 400nm energy to 680nm energy, which is the exact amount of energy required for PSII to split a water molecule into H2 and O (or 1/2 O, as two water molecules are split into 2x H2 and 1x O2).

That excess energy has to go somewhere, which it does - in the form of kinetic energy or heat, which raises the leaf temperature. Which can also lead to cellular photo-oxidation.

In other words, light bleaching.

The moral of the story is you need the right balance of spectra so as not to saturate any one particular pigment – because once saturated, any additional photons are wasted, and also start to damage the cells.

The most efficient fixture may not be the best one for growing.

 

[CharlesU Farley]

I had about 3 things going on. I'm pretty sure I usually get it right

We _all_ fuck up sometimes.

When you provide so much technical / scientific information, it can be difficult to be correct _all_ the time, when you're juggling so many things / threads.

It's a whole lot easier for these "one line bro science experts" to spew out a platitude for a bunch of Likes, than it is to provide a logical, scientific, and most importantly _understandable_ concept to people who don't have the same knowledge base you do.

You do good here.

 

[Ca++]

We _all_ fuck up sometimes.

When you provide so much technical / scientific information, it can be difficult to be correct _all_ the time, when you're juggling so many things / threads.

It's a whole lot easier for these "one line bro science experts" to spew out a platitude for a bunch of Likes, than it is to provide a logical, scientific, and most importantly _understandable_ concept to people who don't have the same knowledge base you do.

You do good here.

I face planted lol but thanks for watering me in quickly

@Prawn Connery That was a grade A post