New Grower GPW...What?

[TxOld Dude]

In fact photons are different between themselves, they can carry different amount of energy.
The manifestation of those differences are what we percieve as colors. "Blue photons" have more energy than "red photons" and the PAR is a term describing the energies(colors) needed by plants to make photosynthesys. Led lights have better efficency in terms of emission of selected wavelenghts(=colors, energy) than hids.

@pop22
If you find it, please post the link, I'm pretty sceptic about that one. Thanx

That involves wave-particle duality physics. More than I want to get into!

For other folks info:
Photons don't just go for a bit then stop unless they are stopped by something in their way. LED vs HID or any other, it's the volume of photons involved and the amount that are directed to a specific point in space. PAR measures the volume of photons within a specific range of frequencies from 400nm-700nm. If you were to have the same exact LED at the same distance and change the lens from 30 degrees to 45 degrees the PAR would fall off and vice versa from 45 to 30 the PAR would increase.

Re: Penetration
Figure it like this:
Even though water is a poor analogy, it serves the purpose best...

Take garden hose with a twist type spray head. Turn it on just enough for a mist and aim it at a shrub for 30 seconds.The surface of the shrub gets wet but the interior stays dry. Now, don't change the opening on the head but turn up the pressure at the valve. As pressure increases, the volume exiting the hose increase as well and now the mist penetrates deeper into the shrub because more volume is applied within the same time frame.

Like I said, not the best analogy, but for illustration it works. The same is said for electricity when applied to a bulb. At a lower electrical pressure (voltage) the bulb is lit but dim. Increase the voltage and the bulb gets brighter; more photons are excited and exit the filament in the bulb. Efficiency (luminous efficacy) is how many photons (intensity) vs. electrical pressure applied/used. HID uses gases and elements like sodium that when excited emit photons, but require a high electrical pressure (voltage) to do it, therefore not very efficient. LEDs use elements like gallium arsenide and gallium nitride to emit photons with substantially less electrical pressure (3v or so) and heat from the excitation to achieve the same volume of photons.

I guess the point is that the capacity of the material to emit photons at a desired volume and the voltage necessary to achieve excitation is what determines the best "delivery system".

Florescents: Not much bang for the buck. Requires a ballast to step up the pressure. Low excitation and photon volume at the specified voltage due to the chemical used in the tube (low-pressure mercury vapor). Low photon volume=low penetration (remember the shrub?).

HID: Requires a ballast to step up the pressure. Better output due to the chemicals (sodium bromide or iodide) ability to emit more photons than fluorescent. But uses lots of power and generates lots of heat doing it.

Plasma: Florescents on steroids.

LED: Best bang for the buck due to lower power requirements and better efficiency. Still have a ways to go on grow lamps though, I think. It seems they are still missing something. Hard for the "regular" grower to compare HID to LED as regards to efficiency and power usage as LEDs are rated in PAR while HID and everything else is still rated in lumens. A common comparative needs to be instituted to make it easier for the non-techy to determine how LEDs equate to everything else non-LED.

Just my 50 cents...
Fish

 

[gradolabs]

To be fair, it's actually more of a planck relation thing and it's deceptively simple. E=hc/λ, where the energy is directly proportional to h, plancks constant multiplied by c, the speed of light (if you're wondering that stands for constant, i.e. the universal constant) , and that sum is divided by the wavelength of the electromagnetic radiation. Kid stuff.

And yes, PAR values are terribly important - best when measured in micromoles per square meter per second at critical wavelengths. And remember a mole of something is 2[SUP]79[/SUP]. That's avocados number.... I mean avogadro. But photons are small, probably massless, so who cares. Pile 'em on till you bleach your colas starch white. Then back em off a bit. (dont listen to me)

My take on gpw, or any statistic really, is yeah you can use it as a benchmark, but at the end of the day there's so many bloody variables it's very easy to misconstrue facts or misrepresent the truth. If the bud's good, smoke it, I say.

 

[TxOld Dude]

...more than I wanted to get into! Yeah, but it sucks to have to take 2-3 grows and spend obscene amounts of cash to figure it out.


They really need to come up with a good comparative measurement across the board for all lighting. It's a royal pain in the ass to figure output, PAR...lumens...watts, and try to equate that to a choice when selecting a light. Most regular people are used to "watts", which is useless, to relate to brightness!
C'mon industry, pick one for everybody and let's rock!

 

[flat9]

If i can find it again I'll post a link that contradicts that idea,ie, vertically hung bulbs are the least efficient wat to use HPS or MH due to the radiation patterns of these light. they are much more effiecient when used with well designed hoods and the bulb in the horizontal position

Not sure I agree bro. There's necessarily quite a bit of loss, as well as increased distance, for the radiation emanating from the top 180 degrees of the bulb .... loss in the reflect, and also adding unnecessary distance. And most importantly, DITCH THE GLASS!!!!!!! Any time you put a piece of glass in between your bulb and your plant, the glass absorbs probably 15-30% of the light. Cool tubes especially are bad (curved glass seems to be worse). I took a lux meter recently and a cooltube and it was a solid 20-30% intensity that was lost on a 600. That's an extra 150 watts. For that 150 watts I could extract heat from the room at 4 times the speed (total overkill).

Anyway, besides bare bulbs, the benefits of vert is that you can grow plants around them 360 degrees. The other benefit is penetration -- the inner colas aren't blocked by the fans up top. This comes typically at the cost of increased plant numbers but look at Heath's 2.2 gpw grow, for instance using NFT:

http://www.rollitup.org/hydroponics-aeroponics/149998-heaths-flooded-tube-vertical-6.html

He also did pretty well (1.5 gpw+) just doing trees w/ RDWC:

https://www.icmag.com/ic/showthread.php?t=181239

Heath Robinson is a master grower, of course, but I've never seen a photoperiod grow w/ a 3 week veg w/ 2.2 gpw that used horizontal lights. Nor have I seen a photo grow getting 1.5 or 1.76 gpw with a 4-5 week veg using horizontals. You may be able to get closer w/ Gavitas, but I digress. The dual-ended bulbs do look promising though....

 

[flat9]

...more than I wanted to get into! Yeah, but it sucks to have to take 2-3 grows and spend obscene amounts of cash to figure it out.


They really need to come up with a good comparative measurement across the board for all lighting. It's a royal pain in the ass to figure output, PAR...lumens...watts, and try to equate that to a choice when selecting a light. Most regular people are used to "watts", which is useless, to relate to brightness!
C'mon industry, pick one for everybody and let's rock!

Yeah, even PAR to be honest is a somewhat stupid measurement because it fails to account for the RATE of photosynthesis at a given wavelength. You'd much rather have 1000 umol of photons per sq meter per second at 660 nm than at 580, since the absorption rate is much higher for red than for yellow. California lightworks came up with something that makes SOOOOOOOOOOO much more sense. Basically you premultiply the spectrum by relative rates of absorption before integrating. See slides 18-19 here:

http://californialightworks.com/info/CLW_Pres.pdf

Shit, the link seems to be broken. But the process is exactly as I described, and this gives you an apples to apples comparison (that reflects your preference of blue and red over yellow or green).

Still, this doesn't given you a footprint. What the industry standard SHOULD be in my opinion is this adjusted PAR metric over a 4' x 4' footprint at 24". You can pretty much figure out what will happen at different heights from that.

 

[flat9]

Hmm seems that pdf is down for good, but there's some more interesting info I found here:

http://solaroenergy.com/wp-content/uploads/2011/02/OSRAM-Horticulture-Application-Grow-Lights.pdf

Slide 5 is essentially what I'm talking about. We shouldn't be equally weighting each part of the spectrum (as in the graph on the left of slide 5), but instead multiplying whatever reading the spectrometer comes up with at a particular wavelength by the absorption rate at that wavelength (as in the DIN 5031-10 curve on the right on slide ) before we add it all up and call it PAR ... this is what "adjusted PAR" is.

 

[flat9]

Apparently there's an "official" name for this adjusted PAR curve. It's called "yield photon flux," and every plant has its own curve. I wonder if it will ever get to the point that lamps can be dialed in to the precise crop?

 

[TxOld Dude]

You can with some Chinese LED companies. I've heard of people getting their own "spectrum blend" on a 1-4 unit basis. Guess it depends on how much one wants to pay as I'm sure there'll be a premium.

 

[Balarama]

Cheers flat9,

YPF makes even more sense than PAR, but afterall they should be the same thing.
The ypf changes during plant grow phases, so it will be a big challenge to possible researchers of this field. But the benefits of such knowledge would have tremendous impact on indoor applications and light development.
One can think of a led pannel with integrate sensors of some sort, which could adapt the spectrum and intensity(+ focus) accordingly to the plants needs, automatically
Too sci-fi? I think not.

 

[flat9]

Yeah, imagine if the transistors in LEDs could physically adapt to get other wavelengths when necessary. Or even if not, you could just add a bunch of extra LEDs which flip on and off depending on what it reads from the plant, making an entire feedback control system for cannabis. Ha ha ha ha. Ok nerding out pretty hardcore here but its' a fun idea.