UV Light and Terpenoids

[elmanito]

Gavita_pro_300

The GAVITA Pro 300 LEP (Light Emitting Plasma) is a solid state horticultural plasma light fixture. There are no moving parts in the fully sealed housing, improving the reliability. The light source is a LUXIM STA 41.02 LiFi module which has a rated average life of 30,000 hours. The glass wide spectrum filter allows for low quantities UVB light to pass while shielding you and your crop from UVC. The Miro aluminum reflector generates an even square light pattern. The absence of heat radiation in the light allows you to hang the lamp close to your crop, or to add the light without adding extra heat radiation to your crop.

Features & Benefits

* Solid State Plasma: no moving parts, fans or sound
* Horticultural quality fixture
* Miro Aluminum reflector, square light pattern
* High quality glass filter
* Full spectrum light incl. UVB
* Rated average life of 30,000 hours

Specifications

* Input Voltage: 207 - 277 Volt (+/- 3%)
* Input Current: 1.3 Ampere at 230 Volt
* Input Power: 300 Watt (+/- 3%)
* Power Factor: >0,99
* THD: <10%
* Input Frequency: 50/60 Hz
* Electrical Insulation: class 1
* Dimensions: L 593 mm x B 261 mm x H 190 mm
* Weight: Ca 11.7 Kg / 25.8 lb
* Operating Temp. (°C): 0 – 35 C / 32 - 95 F
* Case Temp. (°C): 75
* Relative Humidity: 25 – 70% (non-condensing)
* Reflector Material: Miro™ aluminum high efficiency reflector, square field
* Glass Filter: 4 mm Crystal Clear Low-Iron float glass with wide spectrum grow light transmission
* Covered Area: 3'x 3' at 1' distance, 4'x 4' at 1.25' distance
* Light Source: LIFI STA 41-02 module
* Luminous Flux: 18,000 lumen (indicative)
* PPF: 300 μmol (calculated from spectrum analysis)
* Color Temperature: 5600 K
* CRI: 94
* Operating Position: Light source pointed downward +/- 90
* Accessories Included:
o Brackets
o Power cord

http://www.gavita-holland.com/index.php/products/proline/prolinefixtures.raw?task=callelement&item_id=241&element=d32a3a68-b3fa-4136-9deb-182d60979c50&method=download&args[0]=9216fc8c4a52a79176c75a415d76bcee

Namaste

 

[knna]

Before continuing with the very interesting debate of how to know better the light we are using, time for Excel sheets (well, actually I use Open Office with .ods format, but Ill try to upload them on .xls Excel format aswell).

I was correcting my sheets for the more accurate coefficient to calculate micromols for a given wavelength, when I saw a sheet I downloaded from an article of Gerald F. Deitzer. It has spectral and irradiance measurements for the different lamps used in the experiment (Sunlight, sulfur plama, Xenon*filter, Sylvania MH, EYE 6500+barrier and Lucalox HPS) and later tables with all spectra along different weighting functions (photosynthesis by Cree, UVB-BE by Cadwell, Phytocrome photoequilibria by Sager and garder, phototropism, erithema, UVC damage...). Coefficients comes on 2nm increments, good enough. So Im going to be able to find exact weighting of Vitalux typical spectrum for UVB-BE (although 2nm table does it a little longer, I usually use 1nm tables that I need to adapt).

My sheet analyze spectrum introduced to obtain some parameters related just to spectrum itself:

-LER: Luminous Efficacy of Radiation.Lumen produced for each optical watt (1931 CIE based)

-PPF/Klm: micromols of photons for each 1000lm. Useful for converting mesurement from a simple luxmeter at top canopy to micromols irradiance.

-PYF/Klm: same ratio for PYF, weighted micromols of photons by McCree curve for cannabis. McCree curve is obtained from absorbed photons (actually, its a related quantum yield curve), thus the right way of using it is by derating incident photons by absorbency at each wavelength. A step often forgotten on lots of studies. Sheet uses averaged absorbency of cannabis for several varieties and stage of development.

Anyway, any weighting function only provides an insight, in this case, of photosynthetic potential. Photosynthetic weighting curves are calculated with monochromatic wavebands alone (2nm wide for both the most known from McCree and Inada), thus they dont take in account synergies between wavebands. Small correction for broadband light sources, but not for spectrum composed of selected narrow wavebands. And of course, they are only valid for low light levels, way below saturation points, as that way is how they were calculated.

PUR/Klm: same for Inada curve. As Inada curve is obtained based on incident watts, that way is how its applied. Result is weigthed PAR watts. In this case, cannabis absorbency dont apply, result is an average of 27 plant species.

PYF/PPF: Weighted photons by McCree between micromols of photons. A single figure that resumes how good is the spectrum inducing photosynthesis in cannabis at unsaturated light levels (and all the other limitations).

PYF/PPF wide: same but integrating the full range 380-780nm instead of the default 400-700nm.

PUR/PAR W: PAR watts weighted by Inada curve between PAR Watts. How good is the spectrum according to Inada conditions.

R/B= Red (wide sense, 600-700nm) / Blue (400-500nm) ratio, both for uE (micromols of photons) and optical Watts.

R/Fr: Red to Far Red ratio, too for both uE and W. Narrow range, 651-670nm/716-735nm. For more accuracy, next point.

φ Pfr/Ptot: Far red phytochorme between total phytochomes (far red +red). Phytochrome static photo equilibrium by extinction coefficients as defined by Sager. Many biological reaction very related. In general, valid for growing spectrums are characterized by this figure over 0.75.

Percentages of Blue (400-500nm), Green (501-600nm) and Red (600-700nm), for both uE and PAR Watts. At the bottom of sheet, there is a box with expanded percentages, including 380-780nm.

PPF/PAR W: micromols of photons for each PAR Watt of the spectrum.

Yellow cells are the ones to be filled in the sheet. If you only fill in the ones of the SPD column (the digitalized spectrum), you only gets results above.

If you fill in details of the lamp used:

-wattage, for both bulb and system. Results are displayed for whole system except when opposite is stated.

-lm output, essential figure that must be as accurate and reliable as possible: results below are as accurate as is lumen rating.

Price and useful life, if you want to compare different lamps to decide what to buy. If not filled in, results related remain empty.

Sheet show radiometric efficiency of bulb and system (output watts/input watts, except when stated the opposite, for 400-700nm), absolute emission (uE and PAR W), and weighted by McCree/Inada (PYF and PUR respectively), system lm/W, heat load, of bulb and system and if desired, ratios of all this according to price and useful life.

Absolute emission of bare bulb, as its what is usually known.If using a hood, it would be required to know the efficacy of the hood redirecting light and derate results accordingly. If emision for the system bulb+hood is known, then its perfect and you can use it directly on the sheet.

I uploaded them as .pdf. Change extension for .ods (Open Office) or .xls (Excel, when noted).

BA has a collection of typical lamps analyzed. BA-Model are the empty sheets, on 1nm, 5nm and 10nm version. Copy and paste to another sheet and fill in. Hand_digitalize is a tool to help digitalizing SPDs. Includes a collection of already digitalized SPDs.

 

[BudZad7]

UVB or not to UVB???

UVB or not to UVB???

Hi All!! Very informative info!!!! Tried all these various bulbs ,tubes etc...For a boost in Resin production, use the simple pain in the butt method!!! LOL!!! Here's an example ( OG Kush is very resinous already, but an experiment was done on 2 plants side by side, same nutes,light etc...One plant was tacked, with a thumbtack in the base of the plant, and the other plant was not tacked......the tacked plant was more resinous......and from hence forth all plants are tacked after 1 month of flowering, also a pak of tacks cost a Dollar, compared to all those lights......

 

[knna]

Hay elmanito! Thanks for sharing! I have forgotten the new plasma lamps (induction MHs).

Its true that they seems as the best choice for giving an integrated blast of UVB. Indeed, it need to be filtered for UVC aswell, so its just to use a glass opaque to UVC but not to UVB! Ive seen that model from gavita in action, pretty impressive (sadly, the ballast is not very efficient, because the bulb does, the typical problem of induction lamps)

Never use it without filter! UVC is really dangerous. Not large amounts present, but we need to avoid any amount. Serious burn danger, specially for retina.

 

[elmanito]

Hay elmanito! Thanks for sharing! I have forgotten the new plasma lamps (induction MHs).

Its true that they seems as the best choice for giving an integrated blast of UVB. Indeed, it need to be filtered for UVC aswell, so its just to use a glass opaque to UVC but not to UVB! Ive seen that model from gavita in action, pretty impressive (sadly, the ballast is not very efficient, because the bulb does, the typical problem of induction lamps)

Never use it without filter! UVC is really dangerous. Not large amounts present, but we need to avoid any amount. Serious burn danger, specially for retina.

No thanks at all.If i find more info i let you know, but you also thanks for the info, although i can't open the files you added, not even with my own open office.

Normally you only find UV-C high in the mountains and yes it is of the UV the most dangerous, specially for your skin & eyes.Always wear glasses & protect your skin.

Namaste

 

[spurr]

spurr I believe you said you saw an increase in thc production with uv-b light? How did you measure this effect?

Using Thin Layer Chromatography, see this post of mine for info about using TLC and cannabis and this post of mine for a YouTube video showing TLC in action. I used TLC and spot density comparison with JustTLC. It's not quantitative in the sense of weight of THC, but it is quantitative by showing if there is an increase in THC (by comparing the spots of extracts from buds irradiated with UV-b and not irradiated with UV-b). This coming year I plan to conduct more and better testing, and use quantitative measurements of THC (using HPTLC and GC) for very accurate results.

 

[knna]

We will have to agree to disagree

I strongly disagree this statement

Talking is how people understand mutually.

Indeed, we mostly agreed. I agree with most of you posted, and most of it not invalidate most of my statements. Simply, you missed my point. Im not being able to communicate well enough. Im not English mother language, but Spanish. You can notice it by my bad spelling (not so much lately,I installed an English spell checker and disabled Spanish one, at the end, Im good spell checker in my language), my use of words with more meaning that Im aware of (e.g, strain), and my difficulty explaining complex things like this.

I prefer to not going answering your long post point by point. First because I agree most (later we can talk of what I disagree), second because sometimes trees dont allow to see the forest. And the problem here is of concept. You are not understanding what I want to mean.

Im not saying irradiance measurement are not valid. I think they are essential to carry any experiment/study properly. For some things, its the only way available. Im all day measuring local irradiances with my spectroradiometer.

I just pointed up its inherent limitations. Botanist uses it because its the best they have to do the task. And anyway, its required. But that not mean is perfect. Its not. Using it, and specially when not fully understanding how lighting works (and many botanist dont), have limitations. It serves for what it serves.

On the other hand, calculating irradiances from known radiances is very useful. It not replaces (it cant) actual irradiance measurements, but add additional info that serves to put irradiance measurements on perspective. Thats the main point.

Second, it allows some things that you cant do easily with irradiance info. As calculating the power of the lamp you need to use for a given space.

This way is how this topic came to the thread. I posted the radiance of the Vitalux, and did some maths based on it, in order to know what area it could be lit providing enough average irradiance. You asked me about it and I explained my kind of reverse thinking that leads to that process, and how to interpret it. Average irradiance calculated is just a guideline that simplifies selecting the bulb used. Later, actual setup must be controlled with a light meter, measuring irradiances at leaves level.

Third, and this came later, when you know the spectrum of the lamp, the absolute radiance, and the light pattern distribution, you can calculate very accurately actual irradiances (at least, at top canopy), whatever is the setup, its wall reflectivity and so on. That is my field of expertise, and I can ensure you currently with a home PC you can simulate via sofware irradiance obtained at a plane at any distance and size of the lamp or lamps used (if lamps are of different spectrum, then sofware and simulation is way more demanding, requiring to do it by steps and later integrate it). That this is not for all, I fully agree. Indeed, many of we are talking is not for all. But is perfectly possible technically and Im used to do it. And its a tool that a researcher can use. Anyway, I always try to help using my experience on this.

But doing sofware simulations is not the main possibility that allows using radiance. You dont need to do it at all. But knowing the absolute photons falling on a given volume of plants is great to put irradiance measurements on perspective. You can use it or not. But choosing not to use it because botanist didnt in the past is a poor cause (as it has its own reasons not related to this info not being very valuable). Science is about continue improvement of techniques used to obtain relevant data.

Each set of data is valuable in its own context. Its difficult to know about everything, and Ive seen mayor scientific to fall in procedure mistakes, specially when trying something ahead its expertise.Im always calling to know how different procedures were developed, and the conditions at which they work perfect, fine, or simply, wrong.

I offer a way to obtain very valuable additional info about lighting, and that overcomes some limitations of other methods used. These tools arnt excluyent of other, but complementary.

 

[knna]

No thanks at all.If i find more info i let you know, but you also thanks for the info, although i can't open the files you added, not even with my own open office.

Normally you only find UV-C high in the mountains and yes it is of the UV the most dangerous, specially for your skin & eyes.Always wear glasses & protect your skin.

Namaste

I downloaded it and works.

Have you changed the extension to .ods? If so,maybe you have a non actualized Open Office version. I use 3.2. Latter versions used .xsc format.

If changed the extension and it dont work you can either actualize open Office (its free) or use the excel format sheets. Open Office is able to open .xls archives.

 

[spurr]

@ all,

here is a good example of a quantum sensor for UV range providing irradiance as umol/area/second, it's not prefect because it includes the UV-a range, but I figured I would post it anyway:
http://www.apogeeinstruments.com/UV/

 

[spurr]

I was correcting my sheets for the more accurate coefficient to calculate micromols for a given wavelength, when I saw a sheet I downloaded from an article of Gerald F. Deitzer. It has spectral and irradiance measurements for the different lamps used in the experiment (Sunlight, sulfur plama, Xenon*filter, Sylvania MH, EYE 6500+barrier and Lucalox HPS) and later tables with all spectra along different weighting functions (photosynthesis by Cree, UVB-BE by Cadwell, Phytocrome photoequilibria by Sager and garder, phototropism, erithema, UVC damage...). Coefficients comes on 2nm increments, good enough. So Im going to be able to find exact weighting of Vitalux typical spectrum for UVB-BE (although 2nm table does it a little longer, I usually use 1nm tables that I need to adapt).

Cool, can you like to the G.F.Dietzer paper? Thanks

 

[spurr]

Normally you only find UV-C high in the mountains and yes it is of the UV the most dangerous, specially for your skin & eyes.Always wear glasses & protect your skin.

UV-c isn't high in the mountains, it's really well filtered out by gasses in the atmosphere. There can be some UV-b at the very high elevations, but it's not high.

 

[OsWiZzLe]

http://www.pnas.org/content/early/2010/10/27/0914532107.abstract

Negative feedback regulation of UV-B–induced photomorphogenesis and stress acclimation in Arabidopsis



Abstract
Plants respond to low levels of UV-B radiation with a coordinated photomorphogenic response that allows acclimation to this environmental stress factor. The key players in this UV-B response are COP1 (an E3 ubiquitin ligase), UVR8 (a β-propeller protein), and HY5 (a bZIP transcription factor). We have shown previously that an elevated UV-B–specific response is associated with dwarf growth, indicating the importance of balancing UV-B–specific signaling. Negative regulators of this pathway are not known, however. Here, we describe two highly related WD40-repeat proteins, REPRESSOR OF UV-B PHOTOMORPHOGENESIS 1 (RUP1) and RUP2, that interact directly with UVR8 as potent repressors of UV-B signaling. Both genes were transcriptionally activated by UV-B in a COP1-, UVR8-, and HY5-dependent manner. rup1 rup2 double mutants showed an enhanced response to UV-B and elevated UV-B tolerance after acclimation. Overexpression of RUP2 resulted in reduced UV-B–induced photomorphogenesis and impaired acclimation, leading to hypersensitivity to UV-B stress. These results are consistent with an important regulatory role for RUP1 and RUP2, which act downstream of UVR8–COP1 in a negative feedback loop impinging on UVR8 function, balancing UV-B defense measures and plant growth.

 

[knna]

Cool, can you like to the G.F.Dietzer paper? Thanks

Oh, sorry, I forget to upload it.

Changed too to .pdf, actually .xsc. As it was more than 1MB, page dont let me to upload it as it, so I have to zip it.

So download, change extension to .zip, unzip and you get the .xsc sheet.

 

[spurr]

We will have to agree to disagree

I strongly disagree this statement

Talking is how people understand mutually.

Indeed, we mostly agreed. I agree with most of you posted, and most of it not invalidate most of my statements.

Yup, I do agree with most of what you posted too. I was only referring to your stance that using inverse square law (radiance > irradiance) is valid for light sources most cannabis growers use; and my stance that it is not valid (due to the issues I pointed out in regard to point source light, like reflectors, etc.).

Simply, you missed my point. Im not being able to communicate well enough. Im not English mother language, but Spanish.

I doubt I misunderstood your point, I think I understand you well. You write very well in English for it being your second language, you write in English better than many Americans!

However, it seems you misunderstood my main point, re: why we can't use (with high degree of accuracy) the inverse square law for HID lamps in reflectors, or with LED arrays when the the 'five-times' rule is not exceeded.

You can notice it by my bad spelling (not so much lately,I installed an English spell checker and disabled Spanish one, at the end, Im good spell checker in my language), my use of words with more meaning that Im aware of (e.g, strain), and my difficulty explaining complex things like this.

Again, I am very impressed with your mastery of the English language, especially written. You spell and write better than 1/2 of ICmag members

On the other hand, calculating irradiances from known radiances is very useful. It not replaces (it cant) actual irradiance measurements, but add additional info that serves to put irradiance measurements on perspective. Thats the main point.

Yes, I understood that to be your main point. But, my main point is we can't use radiance to find irradiance (with high degree of accuracy) if the point source light (ex. HID lamp) is in a reflector. And if a LED array does not exceed the five-time rule, the LED array can not be used (with high degree of accuracy) with the inverse square law, because if the LED array does not exceed the five-times rule the LED array is not a point source light.

Using radiance to find irradiance works by the inverse square law, and the inverse square law works only with point source light. And if the point source light (ex. HID lamp) is in a reflector, or passes through a collimating lens, then we can not use the inverse square law with reasonable accuracy. Also, a LED array is only a point source light if it exceeds the five-times rule of "far-zone", i.e. "far-field".

Second, it allows some things that you cant do easily with irradiance info. As calculating the power of the lamp you need to use for a given space.

Yes, but only if when using the inverse square law is valid, and the inverse square law is not valid (with high degree of accuracy) for a HID lamp in a reflector or for a LED array that does not exceed the five-times rule. The margin of error is too great for accurate conversion of radiance into irradiance.

This is about the rules governing the inverse square law. Very often people misunderstand the inverse square law as being usable in all situations, and that is not a correct assumption.

This way is how this topic came to the thread. I posted the radiance of the Vitalux, and did some maths based on it, in order to know what area it could be lit providing enough average irradiance. You asked me about it and I explained my kind of reverse thinking that leads to that process, and how to interpret it. Average irradiance calculated is just a guideline that simplifies selecting the bulb used. Later, actual setup must be controlled with a light meter, measuring irradiances at leaves level.

Yes, however, you seem to have missed my post about why you can't use the inverse square law (with high degree of accuracy) with the Osram, or the MegaRay:

https://www.icmag.com/ic/showpost.php?p=4064873&postcount=193
"What I mean is X umol/second (uE) at lamp doesn't well correlate to Y umol/area/second at canopy (via. inverse square law) if we are using a point source light within a reflector (esp. 'pebbled' reflector), or that passes through a "collimating" lens. The same holds true for point source light that becomes diffuse via. diffuse transmission, for example, passing through opal glass.

The problem with mercury vapor lamps like the Osram and MegaRay, is the bulb is within a reflector and the light passes through collimating lens. Not only that, but the Osram lamp face is made of opal glass and thus provides diffuse transmission. Also, using the inverse square law is generally most accurate when the irradiated area is large, relative to the size of the bulb. That is why incandescent and HID lamps can be used with the inverse square law when they are not placed in a reflector. However, both the Osram and the MegaRay are 'flood' style UV-b lamps, they are very directional in terms of a small footprint, they do not provide direct light, they provide diffuse light. Thus, the inverse-square law is not really applicable (in terms of worthwhile accuracy) for either lamp, at least in my opinion.

Considering the issues about the Osram and MegaRay 'zoo' UV-b lamps I listed above, using the inverse square law is not valid, IMO anyway. That is why I used a UV-b meter, and why I suggest others use a UV-b meter too. What matters is the irradiance at canopy, not radiance at lamp, because radiance at the lamp can't be converted into irradiance at canopy with those two lamps with a reasonable degree of accuracy using the inverse square law, at least in my opinion."
​

Third, and this came later, when you know the spectrum of the lamp, the absolute radiance, and the light pattern distribution, you can calculate very accurately actual irradiances (at least, at top canopy), whatever is the setup, its wall reflectivity and so on.

There are major caveats you are not mentioning, such as the large error margin when using the work of Ivo Busko and your spreadsheet. See my next post for more info on flaws of the work by Ivo.

But doing sofware simulations is not the main possibility that allows using radiance. You dont need to do it at all. But knowing the absolute photons falling on a given volume of plants is great to put irradiance measurements on perspective. You can use it or not. But choosing not to use it because botanist didnt in the past is a poor cause (as it has its own reasons not related to this info not being very valuable). Science is about continue improvement of techniques used to obtain relevant data.

You are missing my point: you can't use the inverse square law (with accuracy) for HID in reflector, or a LED array if it does not exceed the five-times rule (because in that case the LED array is not a point source light). And you can't use the inverse square law (with accuracy) with the Osram or MegaRay UV-b lamps.

I am not choosing to disregard use your suggestion of the inverse square law because it's not used by plant physiologists. I am choosing not to use your suggestion because it can't be used with reasonable accuracy by most cannabis growers due to the reasons I wrote about above. If we all used HID lamps without reflectors, or used LED arrays that qualify as point source light, I would agree with you 100%.

Each set of data is valuable in its own context. Its difficult to know about everything, and Ive seen mayor scientific to fall in procedure mistakes, specially when trying something ahead its expertise.Im always calling to know how different procedures were developed, and the conditions at which they work perfect, fine, or simply, wrong.

I agree, but you are ignoring the rules of the inverse square law. That is why we do not agree, I realize the inverse square law can be used in some situations, but not for HID in a reflector, and not for the Osram or the MegaRay (with high degree of accuracy).

I offer a way to obtain very valuable additional info about lighting, and that overcomes some limitations of other methods used. These tools arnt excluyent of other, but complementary.

They would be complementary if we used a point source light that held to the rules of the inverse square law. But most cannabis growers do not use such as point source light, ex., HID not in a reflector, or LED array that is far enough away from canopy to exceed the five-times rule.

Read this post of mine for info about the five-times rule and LED arrays, I think it might have gotten lost in the mass of posts: https://www.icmag.com/ic/showpost.php?p=4066408&postcount=199


No matter what, I am glad to have you here and I highly respect you.

 

[spurr]

Please, for those not inclined to maths, skip directly this post.

Its not required at all for experimenting with UVB, or for lighting a grow, or for growing at all. Just for those who likes to know things in deep and likes maths.

Thanks for posting up the math you used.

I have a very good Excel sheet that is able to calculate almost all parameters you want to know from a given spectrum, you just need to introduce the spectrum. This is an explanation of the way of calculating micromols of photons of each wavelength on a given energy. Excel sheet do it for you, you just introduce wavelenght figure and its done.

I know about your spreadsheet, I think you did a great job on it. And I believe I know what sources you used to do the math from SPD into PPFD, etc. I have all the info and guides you used to make your spreadsheet, I believe. Correct me if I am wrong, but you used the following work of Ivo Busko, no?

"RE: PAR, Lumens, Watts, etc"
http://fins.actwin.com/aquatic-plants/month.9903/msg00462.html

A Comparison Between Light Sources Used in Planted Aquaria
By Ivo Busko
http://web.archive.org/web/20080327114520/www.aquabotanic.com/lightcompare.htm#S-5

"Library of normalized spectral plots"
http://www.aquabotanic.com/lightcompare1.htm​

The problems with using the work by Ivo, and hence with your spreadsheet, is high margin of error in most situations when lamps are not new, or when the lamps are powered with a different type of ballast (ex. magnetic vs. digital) than used by the manufacture to create the original SPD.

I for one really like your spreadsheet, and I am really glad you made it, and posted it for others. Your spreadsheet is worth its weight in gold, especially if a person also has a spectroradiometer to make new SPD's every few weeks/months to account for the changing SPD of the lamp over time. And for spectroradiomteres that do not provide functions in the software to auto-weight the irradiance for plants, your spreadsheet is very useful.

The problem I see in using your spreadsheet when trying to find the PPF, QFD or YPF of non-new lamps (ex. after weeks/months of use), is the increasing error margin over time due to the changing SPD vs. the original SPD from the manufacture.

What I mean is your spreadsheet, and the work by Ivo, is most usable when comparing new lamps; or when using custom made SPDs made every-so-often over the life of the lamp (with the ballast and reflectors used with the lamp to grow cannabis). Due to differences in ballasts between what the manufacture used to make the SPD, and what a grower uses at home there is an error margin, even with new lamps. Also, SPD from manufacture are not all found with the same ballast, and that affects the SPD which makes comparing SPDs from different manufacturers error prone.

The best way to use your spreadsheet, IMHO, would be for someone to test a myriad of lamps, and use the same ballast for each lamp of same wattage, with the same spectroradiometer. Also using the same distance to spectroradiometer, and using lamps of the same age (usage time) and 'on' time (i.e. warm-up time). That would make comparing the SPDs, and using your spreadsheet to find PFPD, QFD, etc., much less error prone.

In regards to your spreadsheet, I agree it's good for comparing new lamps to see which one to buy in regards to providing highest Spectral Efficiency in terms of driving rate of photosynthesis (if using QFD or YPF). But, both QFD and YPF are flawed because they under-weight green light, when high irradiance white light is provided to the canopy.

For example, using the work of Ivo, and hence your spreadsheet, is only valid (with relatively high degree of accuracy) for new lamps due to how SPD changes as lamp ages. And even with new lamps, due to differences between manufactures when making their SPDs, there is an error margin of > 5% using your spreadsheet.

Trying to use an SPD of lamp X when the lamp is week/months old means a larger margin of error due to changing SPD, which will affect the conversion to PPFD, QFD, etc. Also, the SPD from lamp X using a magnetic ballast will be different than the SPD from lamp X using a digital ballast. To use an SPD to find PPFD we would need to make a new SPD often due to how the SPD changes over time as the lamp ages.

I like the spectroradiometer you have, but the signal to noise ratio is too low IMHO; ideally 1000:1 is as low as I would want to go. Apogee makes a nice spectroradiometer that is geared for plants (signal:noise of 1000:1 and from 300-850 nm), and it also will measure irradiance as umol/m^2/second and auto-weight it with YPF (here). I wanted to buy the Apogee PS-200, but I also plan to buy a integrating sphere to make the first action spectrum of photosynthesis of cannabis. And the integrating sphere I want (here) needs an ASD spectroradiometer, like this one (here). I like the Apogee spectroradiometere a bit more than the one from ASD, but I really want to make an action spectrum of photosynthesis for cannabis (at different stages of growth). I think I may try to get both spectroratiometers, but I am not sure yet.

I plan to copy and update the protocols used by K.McCree in his paper "The action spectrum, absorptance and quantum yield of photosynthesis in crop plants" to find cannabis specific data. Until I can afford a good photosynthesis and fluorescence system (here), I plan to use chlorophyll fluorescence alone to quantify rate of photosynthesis, probably with the EARS PPM-300 (here), or possibly the Walz Chl Fluorometer PAM 2500 (here). And this light source that allows custom light quality (custom mix of blue, green and red light) and quantity (up to 2,000 PPFD) is also on my to-get list to study effects of light quality on cannabinoid production, making the action spectrum of photosynthesis for cannabis, etc.


FWIW,

Here is something I wrote a few weeks ago about why converting Foot Candles (FC), lumens or Lux to PPFD is not possible with a worthwhile degree of accuracy. And causes of errors from the work of Ivo Busko and hence your spreadsheet:

You are correct, I have yet to explain how to convert from FC or lumens or Lux, to PPFD. The reason is each different lamp model has a different SPD, thus, the 0.13 conversion (and any other standard conversion) from FC to PPFD is not accurate enough to provide an accurate PPFD.

Given all issues I listed in my last post about why trying to convert FC or lumens or Lux, to PPFD is a non-starter, I hope you can see why I am very hesitant to do so. It just isn't accurate enough, you need to assume at least a 10-20% error margin if using a static conversion factor of 0.13 FC to PPFD under new horticultural HPS lamps vs. traditional HPS lamps. That is why I wrote the only accurate way to convert from FC to PPFD is using a spectroradiometer to make custom SPDs.

Look into Knna's spreadsheet at gardenscure, he complied a good list of lamps and PPFD values (using PAR watt/m^2, spectral output from the lamp's SPD). And even made functions to calculate the lamp Quantum Flux Density, etc., i.e. weighting PPFD with K.McCree's Action Spectra of Photosynthesis.

The problem with Knna's spreadsheet is that it's a bit error prone (~ >5%):

(1) the SPD of each lamp can't be compared with high degree of accuracy (ex. via. PPFD) to SPDs of other lamps unless we know the NIST "absolute irradiance calibration" of each spectroradiometer used to make the SPDs.

Here is a good bit of info from OceanOptics: (link)

Absolute Irradiance uses a lamp of known output (in terms of spectral power) to calibrate the spectrometer’s response at every pixel. This corrects the shape and magnitude of the spectrum, and the resulting spectrum is in terms of power per nanometer...

(2) the SPD data used by Knna for his spreadsheet is found by counting pixels per wavelength from a manufactures SPD (via. computer screen); i.e. adds human error.


(3) the SPD of a lamp will change depending upon the ballast used, thus, unless all lamps use the same type of ballast the SPDs can't be compared with high degree of accuracy, nor can the PPFD from the SPDs. This is why SunPulse lamp company does not provide SPDs.

When a company makes a SPD for a lamp, they do not use a reflector, but most of us do use reflectors for cannabis growing (with HID). That means the SPD from our lamp/reflector/ballast combo will not be the same SPD the manufacture provides; especailly if we use a digital ballast because AFAIK manufactures use magnetic ballasts to make SPDs.


(4) the SPD changes as the lamp ages, thus if you find the PPFD of a lamp using Knna's spreadsheet that PPFD datum will only be good for a small time frame when the lamp is new.

Also, if you use FC to find PPFD via. 'digitized' SPD, that PPFD datum will only be worthwhile from a short time, when the lamp is brand new. That is because the SPD changes as the lamp ages and thus the conversion factor of FC to PPFD changes, it's not static.
​

 

[spurr]

Oh, sorry, I forget to upload it.

Changed too to .pdf, actually .xsc. As it was more than 1MB, page dont let me to upload it as it, so I have to zip it.

So download, change extension to .zip, unzip and you get the .xsc sheet.

I can't download that file due to my security settings, can I PM you my email address and have you email it to me?

 

[knna]

Yup, I do agree with most of what you posted too. I was only referring to your stance that using inverse square law (radiance > irradiance) is valid for light sources most cannabis growers use; and my stance that it is not valid (due to the issues I pointed out in regard to point source light, like reflectors, etc.).

I doubt I misunderstood your point, I think I understand you well. You write very well in English for it being your second language, you write in English better than many Americans!

However, it seems you misunderstood my main point, re: why we can't use (with high degree of accuracy) the inverse square law for HID lamps in reflectors, or with LED arrays when the the 'five-times' rule is not exceeded.

Im glad I was wrong and that you actually followed my argumentation. Thank for say my written English is good, I dont feel so. At least, its way below my ability to explain things in Spanish

Its important to notice how informative can be data about total radiance in the grow room.Now I see you know it, but you think its impossible to get accurate info this way. I disagree at this point, but at least Im glad you notice how much valuable info it may give if it would be accurate enough.

So lets concentrate on why you think is not practical because the low accuracy. If I thought you were not understanding my point was because the insistence on your arguments about why inverse square law is not valid. When I never talked about inverse square law at all. It refer to a virtual condition, useful to explain some things to people starting to study lighting, but almost never found in reality. As most, is near and can be used as simplified way of calculating very special situations. Its not the rule at all, and its not used by lighting designers.

I have criticized many times how people misuse square law too, and more yet, that they actually dont understand it.

In lighting, radiance is the cause and irradiance, the effect (or consequence). Platon (do you write so?) analogy of the cove is very useful to illustrate what I mean. The fire at the start of the cove is the light source. Its proyected to the end, in deep, of the cove. People passing between the fire and the cove proyects a shadow on the deep wall.

When you measure irradiance, you are measuring those proyected shadow. Its almost impossible to know from that the exact nature of the objects that passes behind the fire, because shadow are deformed at the walls irregularities (and more reasons. I dont want to go too far with the analogy, just illustrate the concept).

On the other hand, if you are at the fire, you see directly objects passing behind the fire. When knowing those object is important, looking at the fire is way more useful and accurate. But more yet, it you know how is the bottom wall and have characterized the light source, you can get a good generalized idea of how shadow will proyect on it.

If you are interested on how shadows are proyected, the most accurate thing you can do is directly take a pic of them on the bottom wall. But if knowing exactly the object that caused it is useful, you cant know it by looking at the wall.
Analogy correspondence on this case is total photons for the objects passing and photons density measured for shadows.

Scaling radiance by irradiance measurement is not possible. No matter you take 144 measurements on a 1 m2 area. You wont get any accurate figure that way. You would need to take way more measurements to be able to say with some confidence than scaled up radiance figure obtained is below 15% error. If you look at how light is usually distributed, you realize is nothing homogeneous. There are noticeable differences at 1". More yet, you are using an hemispherical detector, very useful to avoid orientation of detector affects too much measurement, but very bad for integrating measurement on a coherent way. Bad accuracy and unpractical.

You can not know from irradiance measurement the absolute light actually falling on a given area.

So if you want to put in perspective the info obtained by irradiance measurements, you need to go to the light source. You say its not possible to know irradiance from radiance data. I disagree this statement, at least partially. It would depend of the degree of accuracy you need. But knowing the absolute radiance alone, without scaling it to irradiance is yet a very useful data, that help a lot putting in perspective irradiance measurements.

Thats why I thought you were not following me. Scaling to irradiance was not my main point. You are arguing against scaling to irradiance, while first Im saying that knowing the absolute amount of photons given to the space is yet very useful, and not requires any scaling.

One date not replaces the other. Each one has its own usefulness on its own context.

Yes, I understood that to be your main point. But, my main point is we can't use radiance to find irradiance (with high degree of accuracy) if the point source light (ex. HID lamp) is in a reflector. And if a LED array does not exceed the five-time rule, the LED array can not be used (with high degree of accuracy) with the inverse square law, because if the LED array does not exceed the five-times rule the LED array is not a point source light.

Using radiance to find irradiance works by the inverse square law, and the inverse square law works only with point source light. And if the point source light (ex. HID lamp) is in a reflector, or passes through a collimating lens, then we can not use the inverse square law with reasonable accuracy. Also, a LED array is only a point source light if it exceeds the five-times rule of "far-zone", i.e. "far-field".

Once noted that scaling to irradiance is just one other of the possibilities of using radiance data,lets examine your argument against such scaling. That argument is based on low tech lighting technology. No any lighting designer uses the inverse square law to do such thing.

You need to use carefully characterized plots of light emission of bulb used (mainly if its directional), or of the whole luminary. Later, its introduced on ray tracing sofware, able to make very precise simulations. 100% accurate? Sure not, but accurate on the sense of representative of reality. Again, such simulations cant replace actual irradiance measurements, but helps understanding how is the irradiance along all the lit area. With both, accurate simulation, and irradiance measurements giving the most exact info of the grow area, and correcting simulations for the higher accuracy, you have a way better idea of how is the light in the grow, and actually, way better figures in which base your conclusions.

When using large size hoods, its true that get the highest accuracy at relatively short distances is waymore complicated. Not impossible technically, but you need the characterization of the light source is very accurate, and its not easy to find. In general, far field is required for such conversion, so it would be better to avoid large area size lamps, but when using equipment costing 100000$, its possible. You are referring to lab studies, using high resolution spectroradiometer with large integrating spheres costing a lot, and when using those, getting or hiring a high end goniometer to characterize in detail light emission from a relatively large lamp is possible and comparatively cheap.

Its all about the accuracy you want to achieve. This is a MJ growing forum, and resources most people can afford are limited. We usually dont pretend to do scientific work, just experiment on a way results are somewhat valid, by using somewhat well defined protocols and measurement standards. For that, software simulation is a tool cheap (actually, free) able to give very valuable info. When matched with actual irradiance measurements, it allows to get data of very good accuracy, more than enough to work with it with confidence. But if you want still more accuracy, its possible to get it, at a cost, of course.

Anyway, currently you dont need for most botany experimentation light sources of large size that difficulties getting accuracy. Currently, LEDs allows you to do it, with a degree of light output control never dreamed before by botanist.

If you dont use filters or diffuser over the LED array, actually you can treat them as many indicidual point sources, making simulations easy and very accurate. LED's light emiting area is 2-3mm in diameter usually. No more than 4mm. No problem for doing very accurate simulations still at close distances.

Osram, for example, currently gives very accurate optical data of light distribution of their LEDs. With a ray tracing software you can get a very accurate map of actual irradiances at any distance longer than 1" from them. And by the way, if you use LEDs you can design the lamp in a way all the plants in the grow area are under similar irradiance level, which is almost impossible with HIDs without a diffusing cover. Many studies are flawed because they state max irradiance (or simply,irradiance at the center of the area) obtained on the experimental chamber at the given distance of the lamp, but irradiance along the rest of the chamber in many cases (as experiment was designed) is very different.

After saying this, I rarely does this simulations. Very time consuming. Often with the absolute radiance on the area and irradiance data, I get enough. But for some planned experiments which I want to have the best accuracy, Ill do for sure.

But what I want to mean is that with good data about light emission pattern of the light source, its technically possible to do very good simulation of expected local irradiances. And when correcting those maps with actual irradiance measurement, with very accurate results. Unfortunatelly, the condition of well characterized light distribution pattern is not found on at least 95% hoods for the horticultural market.

Only very specialized small manufacturers and the few big ones (Phillips, Osram, GE) gives reliables ones at both bulb and luminary level

Yes, however, you seem to have missed my post about why you can't use the inverse square law (with high degree of accuracy) with the Osram, or the MegaRay:

https://www.icmag.com/ic/showpost.php?p=4064873&postcount=193
"What I mean is X umol/second (uE) at lamp doesn't well correlate to Y umol/area/second at canopy (via. inverse square law) if we are using a point source light within a reflector (esp. 'pebbled' reflector), or that passes through a "collimating" lens. The same holds true for point source light that becomes diffuse via. diffuse transmission, for example, passing through opal glass.

The problem with mercury vapor lamps like the Osram and MegaRay, is the bulb is within a reflector and the light passes through collimating lens. Not only that, but the Osram lamp face is made of opal glass and thus provides diffuse transmission. Also, using the inverse square law is generally most accurate when the irradiated area is large, relative to the size of the bulb. That is why incandescent and HID lamps can be used with the inverse square law when they are not placed in a reflector. However, both the Osram and the MegaRay are 'flood' style UV-b lamps, they are very directional in terms of a small footprint, they do not provide direct light, they provide diffuse light. Thus, the inverse-square law is not really applicable (in terms of worthwhile accuracy) for either lamp, at least in my opinion.​

Indeed a lamp emitting on a narrow angle but diffused into it is the best situation for doing a hand conversion to expected irradiance, provided distance to lamp is large enough compared to its light emitting window's size. But if you have a plot of the intensity emitted on each direction by the lamp (I did a quick searched for Vitalux data on Osram page, unsuccessfully; but maybe its on the plug in for Dialux software), a fast simulation can tell you which irradiance you get with at from given distances and at what size and shape footprint.

Considering the issues about the Osram and MegaRay 'zoo' UV-b lamps I listed above, using the inverse square law is not valid, IMO anyway. That is why I used a UV-b meter, and why I suggest others use a UV-b meter too. What matters is the irradiance at canopy, not radiance at lamp, because radiance at the lamp can't be converted into irradiance at canopy with those two lamps with a reasonable degree of accuracy using the inverse square law, at least in my opinion."

Always you need to check actual situation with the quantum meter. But those simulation can helps you and any one to decide what it requires to buy before doing it and adjust things by trial error or find the bulb election was not adequate.

You are missing my point: you can't use the inverse square law (with accuracy) for HID in reflector, or a LED array if it does not exceed the five-times rule (because in that case the LED array is not a point source light). And you can't use the inverse square law (with accuracy) with the Osram or MegaRay UV-b lamps.

I am not choosing to disregard use your suggestion of the inverse square law because it's not used by plant physiologists. I am choosing not to use your suggestion because it can't be used with reasonable accuracy by most cannabis growers due to the reasons I wrote about above. If we all used HID lamps without reflectors, or used LED arrays that qualify as point source light, I would agree with you 100%.

Conversion to irradiance from radiance uses plots of light intensity on each direction of the space that result via software on accurate irradiance plots via software. Specially with LEDs, it can be done very well and accurate.

No matter what, I am glad to have you here and I highly respect you.

Im glad to find someone able to discuss these topics in deep and make me think about the flaws on my procedures. Feedback and constructive criticism is the way of progress.

PD: Send me a PM,no problem about using email to send documents

 

[knna]

I know about your spreadsheet, I think you did a great job on it. And I believe I know what sources you used to do the math from SPD into PPFD, etc. I have all the info and guides you used to make your spreadsheet, I believe. Correct me if I am wrong, but you used the following work of Ivo Busko, no?

"RE: PAR, Lumens, Watts, etc"
http://fins.actwin.com/aquatic-plants/month.9903/msg00462.html

A Comparison Between Light Sources Used in Planted Aquaria
By Ivo Busko
http://web.archive.org/web/20080327114520/www.aquabotanic.com/lightcompare.htm#S-5

"Library of normalized spectral plots"
http://www.aquabotanic.com/lightcompare1.htm​

The problems with using the work by Ivo, and hence with your spreadsheet, is high margin of error in most situations when lamps are not new, or when the lamps are powered with a different type of ballast (ex. magnetic vs. digital) than used by the manufacture to create the original SPD.

Yes, I based my sheet on the work of Ivo Busko. I believe at the GC thread I explained the process of building it. Although it started for the work of Ivo, and the full concept of the sheet is of him, I quickly realized his method of calculating depended a lot of the SPD introduced.

First, although thought to be used with relative SPDs, as I replied his procedure, I found only works for SPDs representing a fixed lm figure, and its not the rule. I modified the calculation procedure to avoid this. Result is absolutely independent of SPD scale of its match with a lm figure. Only worth the relative values, if they are good, and thats is granted with a good calibrated spectrometer as used by lighting companies.

Second, I developed some way of digitalizing graphs in a way that strongly minimize human error translating figures. Always remain a margin of error due resolution of the graph, of course, but its kept at a enough low figure to end results are accurate. Not a problem at all for spectral analysis alone, and minimal error added when using lamp wattage and lm data.

As I believe you know, I checked results with reliable manufacturers data obtained with high end NIST traceable light measuring systems and results are very close on all figures, for many different lamps. Almost always below 5% difference, and mostly below 3%. Funny thing is my results was always slightly lower than published, and yesterday I found why, the coefficient applied to convert optical watts to photons was 2.9% higher than it should. Meaning that if now I check results, they are going to be surprisingly close to manufacturer data. A margin error way lower than I dreamed this method can provide.

I for one really like your spreadsheet, and I am really glad you made it, and posted it for others. Your spreadsheet is worth its weight in gold, especially if a person also has a spectroradiometer to make new SPD's every few weeks/months to account for the changing SPD of the lamp over time. And for spectroradiomteres that do not provide functions in the software to auto-weight the irradiance for plants, your spreadsheet is very useful.

I developed it for comparing bulbs for growing when all a grower has is his computer. Its excellent for it.

Later i was adding new features as i used it for other purposes. Not looking for the highest accuracy, but to have solid reference data, thats all.

Finally when I got the spectroradiometer which software is thought for photometric applications, when I use it with plants, I need to process SPDs using the sheet, and then its providing highly accurate results because input data is highly accurate as well, specially for relative spectrum and irradiance measurements (I build an integrating sphere and perform absolute radiance measurements with LEDs, but its a demanding task and accuracy cant be high for this, although its excellent for comparative analysis).

The sheet lamp result is as accurate as the lm rating. Unfortunately, I dont trust on specs of many companies. And as you say, there are variation in the output of HID lamps depending of output. On the other hand, output of LEDs tight binned is very consistent, easily characterizable with the right equipment, and more important, easily adjustable to needs.

But lamp aging and output degradation is not a severe issue. Its easy to measure output degradation. Just measure setup of same conditions (position, distance to lamp, on same room, or better yet, dark room) with a light meter, averaging 3 ones. Comparing with the new bulb measurement (actually,if using a HID, you must take as reference measurement at 100h of use, not less) you have a figure to derate light emission with age.

The problem I see in using your spreadsheet when trying to find the PPF, QFD or YPF of non-new lamps (ex. after weeks/months of use), is the increasing error margin over time due to the changing SPD vs. the original SPD from the manufacture.

Not really I problem, I think. Spectrum change is very reduced in percentage points of the relative spectrum. And way more reduced when lamp is emitting more than 85% initial emission, as growers use them before replacing.

On the other hand, weighting functions are only orientative, and anyway little affected by the change of spectrum with age (if initial figure is 75.5%, likely it will stay between 75 and 76 with aging). Absolute PPF wont be very affected neither by spectrum change. Its bulb aging what affect it and setup conditions (electrical and cleanliness), but checking with a with meter you can correct it very well if you want the better accuracy.

What I mean is your spreadsheet, and the work by Ivo, is most usable when comparing new lamps; or when using custom made SPDs made every-so-often over the life of the lamp (with the ballast and reflectors used with the lamp to grow cannabis). Due to differences in ballasts between what the manufacture used to make the SPD, and what a grower uses at home there is an error margin, even with new lamps. Also, SPD from manufacture are not all found with the same ballast, and that affects the SPD which makes comparing SPDs from different manufacturers error prone.

Yes, specially ballast makes a difference. A natural variation from bulb to bulb, at less degree. Affecting total light output, spectral change is way more reduced and difficult to notice on a majority of cases.

If you want the less difference, use an electronic ballast, almost insensitive to electrical input variations and providing a closer output from bulb to bulb.

Very valid for a grower deciding which bulb to get, for accurately characterizing light output, additional measurements are required and accept some margin of error. But a figure of radiance obtained, still with some uncertainly margin, has way better accuracy than any irradiance figure obtained by integration.

With LEDs, its possible to get more uniformity and reduce total output uncertainly margin.

The best way to use your spreadsheet, IMHO, would be for someone to test a myriad of lamps, and use the same ballast for each lamp of same wattage, with the same spectroradiometer. Also using the same distance to spectroradiometer, and using lamps of the same age (usage time) and 'on' time (i.e. warm-up time). That would make comparing the SPDs, and using your spreadsheet to find PFPD, QFD, etc., much less error prone.

Of course, eliminating fully margin error introducing SPD and being able to take reference measurement to correct absolute figures is the best way to use it. But using specs already gives close to reality figures.

In regards to your spreadsheet, I agree it's good for comparing new lamps to see which one to buy in regards to providing highest Spectral Efficiency in terms of driving rate of photosynthesis (if using QFD or YPF). But, both QFD and YPF are flawed because they under-weight green light, when high irradiance white light is provided to the canopy.

Weighting function has three flaws. I only use them for reference, but I dont pay too much attention to actual figures:

-Valid only for unsaturated photosynthesis, while most growers used saturated light levels

-Dont take into account synergies between wavebands. Small difference when using broadband light sources, but more noticiable when using selected narrow bands, as with LED lighting.

-Dont take into account plant adaptability to light spectrums. They only work accurately (at unsaturated P) in the short term. on the long term, actual figures are higher, because plants change their photosynthetic systems to use better whatever light they are receiving.

For example, using the work of Ivo, and hence your spreadsheet, is only valid (with relatively high degree of accuracy) for new lamps due to how SPD changes as lamp ages. And even with new lamps, due to differences between manufactures when making their SPDs, there is an error margin of > 5% using your spreadsheet.

As noted, spectrum change is a minor problem in the practice for short time used lamps. Aging affect the most to total light output, and goes varying very slowly, and its possible to get it controlled and corrected by the adequate measurements.

I dont know actually what is the margin of accuracy it could get. Comparing to manufacturer specs, it seems to be lower than 5%. In the practice, for most growers still a 5% of margin is excellent. For research, it would be desiderable to choose to use the equipments that provides the least differences.

For research, this tool usefulness is mostly when used together with irradiance measurements. When used according to irradiance data, to put them in perspective, specially if aging is measured (not required for short term experiments) a 5% margin error is very useful yet. Still near 10% could be acceptable and still being very useful to put things in perspective.

Trying to use an SPD of lamp X when the lamp is week/months old means a larger margin of error due to changing SPD, which will affect the conversion to PPFD, QFD, etc. Also, the SPD from lamp X using a magnetic ballast will be different than the SPD from lamp X using a digital ballast. To use an SPD to find PPFD we would need to make a new SPD often due to how the SPD changes over time as the lamp ages.

I think you overstates the relative magnitude of SPD change, specially in the short term, and how SPD change with aging affects other magnitudes. if you correct for reduction of output, you get very accurate results and almost negligible differences in calculated PPF, for example.

Actually, those changes affect to all the studies botanist performed with HIDs. Usually they measure irradiance at the start of experiment and forget it. On light related experiments, periodical measurements are taken, but fully ignoring all this.

It dont affect on any significative way the efficacy of spectrum nor the PPF figure. Quantum meters used simply average with a margin of error depending of spectrum used photons along all the measured range and all people thinks its good enough. I think you pretend a level of accuracy that even the best botanist experiments not pretend.

At the bottom you add a problem more associated to calculating radiance with this sheet, the unknown efficacy of fixtures. There are fixtures (precisely those well characterized optically on his light output) which states accurately their efficacy (light out fixture/light emitted by bulb), but they are not found on horticultural companies. And there is another problem more, and its that fixture not only derates light output, but affect too the spectrum on a small degree.

Summing all, you can see why I think using LEDs is a must on horticultural research. And most universities agrees. I doubt on about 2-3 years nobody will use a HID on a botany study again, except for very limited topics requiring it.

I like the spectroradiometer you have, but the signal to noise ratio is too low IMHO; ideally 1000:1 is as low as I would want to go. Apogee makes a nice spectroradiometer that is geared for plants (signal:noise of 1000:1 and from 300-850 nm), and it also will measure irradiance as umol/m^2/second and auto-weight it with YPF (here). I wanted to buy the Apogee PS-200, but I also plan to buy a integrating sphere to make the first action spectrum of photosynthesis of cannabis. And the integrating sphere I want (here) needs an ASD spectroradiometer, like this one (here). I like the Apogee spectroradiometere a bit more than the one from ASD, but I really want to make an action spectrum of photosynthesis for cannabis (at different stages of growth). I think I may try to get both spectroratiometers, but I am not sure yet.

I think mine its more than required. For irradiance measurements, sure. Its a little short for absolute measurements. Anyway, its what I could afford, and probably many more than 99.9% growers are willing to spend.

But more accuracy is always a good thing. If you dont mind, or have the resources for such equipment, all I can say is great for you and for us if you share your findings. I would love to see an action spectrum of photosynthesis for cannabis, specially at Photosynthesis saturating levels. You would need equipment to measure Co2/O2 fluxes too, I think.

I plan to copy and update the protocols used by K.McCree in his paper "The action spectrum, absorptance and quantum yield of photosynthesis in crop plants" to find cannabis specific data. Until I can afford a good photosynthesis and fluorescence system (here), I plan to use chlorophyll fluorescence alone to quantify rate of photosynthesis, probably with the EARS PPM-300 (here), or possibly the Walz Chl Fluorometer PAM 2500 (here). And this light source that allows custom light quality (custom mix of blue, green and red light) and quantity (up to 2,000 PPFD) is also on my to-get list to study effects of light quality on cannabinoid production, making the action spectrum of photosynthesis for cannabis, etc.

I dream with an equipment like all that, really. With it, you can study whatever you want to and get results and conclusions beyond what I believe any grower has ever imaginate. I hope you can join all that and perform such things. Big $$

All the best

 

[elmanito]

UV-c isn't high in the mountains, it's really well filtered out by gasses in the atmosphere. There can be some UV-b at the very high elevations, but it's not high.

The higher you go into the mountains the more UV you will get.The air is thinner.Why do you think that people like e.g. Nepalese has a darker skin. Never seen a Tibetan with a white skin.
UV-index in regions like Oaxacan is > 10 at 1.00 pm during the summer.

Those gasses you talking about is badly affected by environmental pollution.

Namaste

 

[messn'n'gommin']

This paper doesn't go to UV and terpeniod production specifically, but it does go to refuting any reference to UV and plant interaction as being "theoretical."

A UV-B-Specific Signaling Component Orchestrates Plant UV Protection
http://www.pnas.org/content/102/50/18225.full

This one is a summary of studies from "Plant Physiology" by Carlos Ballare.

Stress Under the Sun: Spotlight on UV-B Responses
http://www.plantphysiol.org/cgi/content/full/132/4/1725