LED and BUD QUALITY

[greyfader]

The sun isn’t a good example for indoor single point lighting. For one the bottom of your plant will never be twice as far from the sun as the top. Indoors it’s the norm.

I also have a question for anyone that can answer. What is ppk?

hey buddy! i guess we still have cannabis as common ground. and, even though we've had our differences on issues not related to growing, i still respect you and wish you the best.

the ppk system is an experimental growing system i first designed mentally while in recovery from a liver transplant 15 years ago.

i had 13 years of traditional hydroponic experience before that, and 20 years of commercial salt-water marine specimen collecting, holding, and shipping, before that. so, lots of water experience.

i don't want to derail this thread but it is the system that produced the plants in the link in my signature below.

it is a recirculating, closed loop, soilless system that is highly redundant with overlapping fail-safes to prevent crop loss and is extremely conservative on both water and nutrient use.

it is a flow pattern that can be built to any scale. people have built miniatures in armoires and computer cabinets, small to medium ones in tents and bedrooms, basements, etc, and large warehouse operations.

i have operated 2 warehouse grows, one mine and one where i was the director of controlled environment growing for a large cbd corp.

i will be doing another, detailed, updated ppk thread soon showing the how-to and the theories. this time using led lighting.

i pulled some of the best pics from the thread "something wicked this way comes" under my former handle, delta9nxs, here on icmag.

 

[bloyd]

Anybody using temperature reduction at end of flower with LED's? If so how low? I'm finally able to control environment in a well insulated sealed room and have been dropping temps to upper 60s for finish and I feel I am getting better finished expressions but less weight.

@greyfader are you maintaining high temps for peak photosynthesis till finish?

 

[Rocket Soul]

thank you!

so, we are back on subject again.

you mentioned somewhere in the ancient past of this thread that you thought efficiency was over-rated.

i think that maybe there are different kinds of efficiency.

one is the straight-up conversion of electrical energy to par radiation.

another is the application of the photons in general.

so, there are two hypothetical lights, let's say they are both 1k watts.

but one has a linear arrangement of larger diodes on bars and one has a much greater number of smaller diodes that radiate outward in a circular pattern from multiple, overlapping, point sources.

we have discussed how the elimination of shading creates a greater illuminated surface.

what if the one that radiates outward from multiple point sources hits a greater surface area of the plant from more angles simultaneously than the one with larger diodes on linear bars?

would this not drive overall photosynthesis at a higher or equal rate?

even at a lower electrical efficiency, thereby offsetting the greater electrical efficiency of the other light?

Wow theres so much to bite down on in this one id have to jack the ripper and take it piece by piece. Theres a very real risk of wall of text rambling


You can have many different takes on efficiency, main ones being electrical and output per watt: lums (for human eyes, fairly irrelevant) varios photosynthetic active radiation (PAR) measures which basicly means photon count: standard range 400-700, extended 380 -780 (pbar, i think they call it) or weighted by how good the plant is at using the light by wavelength, by macree curve, think this one is called yPar iirc. Theres a few reasons to not think maccree curve is all there is too it: it was measured by suing individual wavelengths and not a full spectrum. That means you dont get an idea of how different parts of the spectrum interact making it more efficient as a whole: emmerson effect being one of them (interaction between light over and under 700nm give higher photosynthesis than sum of each of those intensities but even here theres more, the effect seems to work best with wavelengths 50nm apart, the best effect in 680 and 730nm).

The reason i think efficiency is over rated is that were not after photosynthesis per se, were after big yields of nice tasty potent buds.

This obviously relates very well with par intensity to the point most people seem to regurgitate Bugbees "spectrum doesnt matter" statement - which is patently false and a missinterpretation of his findings:
Spectrum doesnt matter in the spectrums that he studied. You can never prove negatives. And he was never very creative with those spectrums. I may be miss quoting him somewhat and more so quoting what people think he said.
The spectrums he compared wasnt very creatively conceived, generally standard whites with more or less extra red anf generally nothing below the blue spike of 450nm and unless adding far red almost nothing above 660. Thats 90nm out of 400 with minimal spectral coverage, missing various important action spectrum peaks.
So in my book you need atleast something there, preferably covering bioreactive peaks in action spectrums to even have a good chance at growing good weed. Problem is that doing so means losing efficiency which is what sells lights nowadays. People dont add UV diodes (which are usally actually violets with some uv) but this will always drop efficiency no matter how efficient the diode is: the further towards that end the less photons in one watt of light output. Higher energy photons will always mean less photons per watt. Similar with the +660 range but basicly down to historically inefficient diodes.

Some studies ive seen added a really nice measure which was light utilization efficiency:
How much bud you get per umol of dli. And what do you know, differences of up to around 15% with some more horti leaning spectrums. Thats a big deal. It would take a middling efficiency of 2.4ppf/w and give it the performance of a 2.75 ppf/w with quality benefits aswell.

Weve tried these odd diodes with our grow and had good results, in various ways but id like to resume them most as "growbro": just generally better smells and grows looking "better" to an experienced eye.

If you subscribe to the idea that there are absolute ideal light conditions, even if they are strain dependant, of intensity and spectrum, then efficiency is not in itself the measure for a really great grow light, only how many watts it takes to get there.

If you go for a light which is purely or mostly efficiency first you will never get to that ideal grow situation no matter how many watts you spend. If you try to get a good compromise between efficiency and spectrum, making sure that nothing plant related goes uncovered in the par region and just beyond all you need is to add a few more watts to your grow to get superior results. The extra yield from getting your spectrum really productive will make up for the extra watts you need to get your intensity up. And it seems like these spectrum effects are even more noticeable the higher you go in intensity. Im now in the horti spectrum at 40 or more watts per square foot available camp


On your hypothetical bar versus big spread out board light: this efficiency is a bit more like what migro measures, ppfd/w, the actual results of spread, wattage and efficiency at cannopy levels. And yes diffused light tends to be better as you surmise but the problem with the big round board light is that it will hotspot in the centre since edges dont recieve the same cross light. And the hotspot, centre intensity compared to edges, tend to only get worse the higher you have to hang it. If you keep it real low but at appropriate intensity you get more even light on cannopy. What you described is just really a board, theres ways to get it more even by asymmetric diode density, you can check those vypar bar lights for an idea. Or the 2 driver centre perimeter approach that i think i inboxed you some time ago (or maybe in your thread?)

I did it again, sorry, its a wall of text.

Im going to dropp of, my 5yo nephew just pulled a to the metal sound track of a Lego advert and im so proud