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Lamps & UV isssues

Posted by npthaskell coastal oregon (My Page) on
Thu, Jan 5, 06 at 18:24

In the previous thread, "Why not blue?", the issue came up as to whether bluish fluorescent or metal halide lamps put out too much UV. The "Why not blue?" thread has evolved into a rather technical discussion that may not be suitable for newbies. I hope to keep this thread of interest to newbie gardeners and advanced horticulturalists alike.

The scope of discussion: "Does any lamp (bluish or not) put out too much UV?". "Any lamp" can include solar or filtered solar light. "Too much UV" is from the perspective of the plant, household paint and fabric (will any given lamp damage your home?), or human (skin cancer, blindness).

Also within scope: "Does any given lamp put out enough UV?" Does UV have any positive effects on plants? Also, does UV have any positive effects on the ability of a pollinator or human to visualize flower or leaf color, or the ability of the human to enjoy plant flavor or scent?

I'll start off with a link to a General Electric page, from which you can compare solar to various artificial lamps. Unfortunately, only some of these spectra cover UV. I'll look for a better solar spectrum.

Here is a link that might be useful: GE Spectral Curves

Follow-Up Postings:

RE: Lamps & UV isssues - low res spectra

The product literature for "full spectrum" fluorescent lamps, especially those sold to treat SAD depression, often show what I could call "dumbed down" spectra. These differ from higher resolution spectra presented in the GE link above, which I consider "real" spectra. I assume that the "dumbed down" spectra are redrawn from the "real" spectra.

I do not wish to imply that "dumbed down" spectra are fraudulant (but I have no way of knowing - that is the problem). Assuming that they are honest, they get the point across that a given lamp imitates sunlight (sort far as the human eye can tell). A "real" spectrum, with all of its spikes, can easily overwhelm a newbie; it can even overwhelm me!

In the next several posts, I plan to post links to solar and lamp spectra. In this post, I'll get the "dumbed down" spectra out of the way first.

Two conclusions quickly becomes obvious from these spectra: Some fluorescent lamps put out much less UV than solar! Some "full spectrum" bulbs put out about the same as solar.

1. Lumichrome 1XC versus solar, cool white & daylight

2. Lumichrome 1XX versus solar, cool white & daylight
(UV-A is slightly less than sunlight, UV-B slightly more; the bottom curve looks hand drawn and incorrect)

3. TrueLite versus solar
(this is only mildly dumbed down, the TrueLite spikes have been snipped, and the rest of the spectrum has been rescaled; this is not fraudulant, I have a paper copy of the real raw spectrum from the manufacturer)

4. Starlite versus solar
(here the UV is claimed to equal that of the sun, another brand name is "Excella")

5A. Vita-Lite versus cool white & solar
(the UV is claimed to equal that of the sun)

5B. Life-Lite may be equivalent to Vita-Lite, I assume that the following plots the "real" spectrum of Life Lite (5500K).
(6% of total output is UV-A, 1.3% is UV-B)

Here is a link that might be useful: Another link to TrueLite

RE: Lamps & UV isssues - high res spectra 1

These are links for spectra for "general purpose" fluorescent bulbs.

1A. One of the best sources for fluorescent spectra is a pdf document from Sylvania:

1B. Sylvania Gro Lux Narrow versus Wide Spectrum (pdf):

1C. If these links don't work, try:

2A. Spectra for Philips fluorescents are scattered throughout their product literature. For T5 HO triphosphor 830,835,841 & 850 see:
These spectra are similar to Sylvania T8 and T5 8xx series.

2B. Philips T5 HO "long life!!" triphosphor 830, 835 & 841:
Long life doesn't change the spectra of 830, 835, or 841; there isn't a long life 850 listed.

2C. Philips "Graphica Pro 950", T8, 5300K, CRI98 (not a triphosphor): Ind_Fam/TL-D9HCR/LDPB3_TL-D9HCR_950.GIF
Same as "TL-D 90 deLuxe 950 (URL not shown).

2D. Philips "Graphica Pro 965",T8, 6500K, CRI98 (not a triphosphor): Ind_Fam/TL-D9HCR/LDPB3_TL-D9HCR_965.GIF
Same as "TL-D 90 deLuxe 965" (URL not shown)

2E. Philips "Deluxe Pro 930",T8, 3000K, 92CRI (an enhanced triphosphor) Ind_Fam/TL-D9HLm/LDPB3_TL-D9HLm_930.GIF
There is also a "TL-D de Luxe 930", 3000K, CRI95, that is a 3000K version of the Graphica Pro 950 (URL too hard to post)

2F. Philips "Deluxe Pro 940",T8, 4000K, 91CRI (an enhanced triphosphor) Ind_Fam/TL-D9HLm/LDPB3_TL-D9HLm_940.GIF
The T5 version is similar.
There is also a "TL-D 90 deLuxe 940", 4000K, CRI95, that is a 4000K version of the Graphica Pro (URL is too hard to post)

2G. Philips "DeluxePro 950", T8, 5300K, CRI93 (an enhanced triphosphor): Ind_Fam/TL-D9HLm/LDPB3_TL-D9HLm_950.GIF

2H. Philips "DeluxePro 965",T8, 6500K, CRI93 (an enhanced triphosphor): Ind_Fam/TL-D9HLm/LDPB3_TL-D9HLm_965.GIF
The T5 version differs just a little in the blue region, see below.

2J. Philips "DeluxePro965", T5, 6800K, CRI93 (a triphosphor): Ind_Fam/TL5 HO9/LDPB3_TL5-HO9_965.GIF

2K. Yet another Philips 950 bulb, T8, 5000K, CRI 98 (an enhanced triphosphor)

Comments on these Philips bulbs. All of them seem to have a low UV output. There seems to be different versions of a given color where the CRI is above 90. Hence, there may be up to 3 different spectra for a Philips bulb designated as "950", 3 spectra for a "965", 3 spectra for a "930", and 2 spectra for 940.

I did not bother looking up old fashioned Philips halophosphor "cool white" or "warm white"; I assume that they are the same as Sylvania and GE versions. I could not find spectra for Philips "Daylight Deluxe" and "Natural Sunshine" as found at Home Depot. I assume that Philips "Daylight Deluxe" is similar to that from Sylvania, but Sylvania has higher CRI. I assume that "Natural Sunshine" is similar to any of the 3 types of Philips 950 bulbs, or it could be similar to Sylvania 950 (which is similar to GE's Chroma 50). Philips Graphica Pro 950 is closest to Sylvania 950, except they are not completely identical.

OK, I'm tired. More spectral links tomorrow.

RE: Lamps & UV isssues - high res spectra 2

First, a little addition to the "low res spectra" post. A link for "Excella" (5765K, CRI91):

Second, I noted above that Philips doesn't have a long life version of T5 HO 865 triphosphor. GE does have a "starcoat" long life T5 HO 865 (along with other colors). The following link shows these spectra, which are a little difficult to read because wavelength numbers are slightly shifted to the right:

OK, here are more links

3A. Sylvania is the USA subsidary of Osram; the websites of either contain info that the other lacks. The General Tech Info page for Osram:

3B. Osram "Skywhite", T8 & T5, 8800K, CRI+80 (triphosphor):
As far as I know, the Sylvania web site doesn't have a USA equivalent; but similar lamps are available in the USA as aquarium bulbs (covered later). The spectral curve doesn't cover the UV light output, but some 8800K aquarium bulbs in the USA have low UV output.

3C. Osram Biolux 965, T8, 6500K, CRI95+ (deluxe halophosphor?):
The spectrum barely covers the UV zone; it is advertised as having just a little UV phosphor, sort of a "full spectrum" bulb for pets. The visible spectrum seems to be an enhanced hybrid of Sylvania's Daylight and Daylight Deluxe lamps. I know of no Sylvania product that is an exact match. It looks more like the Philips Graphica Pro 965 with a little more UV thrown in. I think that it would be OK for plants.

3D. Osram Fluora 77
The spectrum doesn't cover the UV, but the visible looks just like the narrow spectrum version of Sylvania's "Gro-Lux" tube, which has a small UV output.

3E. Osram Natura 76
Only a small portion of the UV spectrum is shown. This looks like a narrow spectrum "Gro-Lux" tube with a little triphosphor (especially at 611nm) thrown in. It is designed for food display by the Grocer, but it could be a good plant light.

4. The Skylighter 7200K CRI98 (enhanced triphosphor)
This has such an interesting spectrum, but it doesn't show the UV output. I would love to get my hands on a few.

5. The "Second Sun S-25", 5200K CRI92 is a triphosphor enhanced with 4 additional phosphors. This page compares solar, incadescent, halophosphor cool white, and regular triphosphor spectra. Only a small portion of the UV output of the S-25 lamp is shown; the UV output of the solar spectrum shown on this page seems too low.

6. AgroSun (HydroFarm) has some self-ballasted compact fluorescent tubes up to 200 Watts in "daylight" and "warm" versions.
Only a fraction of the UV portion is shown. These seem to be triphosphors, so I predict the UV output to be low. The triphosphor mix may be enhanced near 525 nm. The peak at ~710 is found in normal triphosphors, but seems a little too high here, as if the spectrum was redrawn a little inaccurately.

RE: Lamps & UV isssues

Its interesting that some of the "human" fluorescents produce a comparable amount of UV to sunlight, relative to the intensity of the light. Did you have some reptile lights in there? They produce 5-10 times the relatve amount of UV as sunlight.

UV is not thought to be important for plants to grow. Plants have been grown successfully though their entire lifecycle with zero UV. So I guess any lamp produces "enough" UV.

Too much UV is tricky to judge. Even a lamp which produces relatively more UV than sunlight is probably ten to a hundred times less intense. You need to be close to a powerful source for a long time to see any damage. I guess that's why metal halide lighting is seen as the main culprit even though all "people" metal halide lamps are shielded (either by a glass envelope on the bulb or by a separate glass shield) to reduce UV levels to near those found on fluorescent bulbs. Using an unshielded 400W metal halide is certainly considered damaging to pigments and most living organisms including people. Sitting with your arm under a reptile bulb would also be damaging (in the same way that UV from sunlight is damaging) but sitting across the room from one wouldn't be.

The levels of UV that are damaging to plants have been studied (people worry about that hole in the ozone layer). These are variable by species and under different growth conditions. Often the first effects to be observed are lower yields, with more serious damage to DNA and other proteins being caused at higher levels. Most plants appear more susceptible to UV damage at lower overall light levels, due to physiological adaptations to capture more light and reduce protective pigment levels. There appears to be no "safe" level, just levels at which plants perform adequately, such as in natural sunlight.

P.S. In your last post on the AgroSun, did you mean 710nm? Or perhaps 310nm?

RE: Lamps & UV isssues

> P.S. In your last post on the AgroSun, did you mean 710nm?
> Or perhaps 310nm?

I meant ~710nm. The red component (I assume) of triphosphors puts out several side bands besides the intense peak at ~611. If you compare triphosphors (eg., Octron 8xx) in the Sylvania document, with the AgroSun brochure, it looks like the 710nm peak is a little too tall.

> Did you have some reptile lights in there?

You just beat me to my next post! ;-)

> UV is not thought to be important for plants to grow...

I have read that UV increases the level of essential oils in mints & relatives and induces color development in flowers (or at least the visualization of flower colors); I have not yet confirmed this in any "primary" scientific literatur. I have read in the primary scientific literature that some of the red pigments are induced by UV (as a defense against UV); I don't have any references on hand. To get beautiful red veins in green Kale or Chard, you MAY need some "extra" UV.

> Sitting with your arm under a reptile bulb would also be damaging
> (in the same way that UV from sunlight is damaging) but sitting across
> the room from one wouldn't be.

The web sites discussing reptile bulbs emphasize that they are "safe" for humans for the reasons you mentioned. But plants are grown under a bank of fluorescents just a few inches away; under these conditions, I would worry.

RE: Lamps & UV isssues -solar & reptile spectra

The spectrum of natural sunlight varies according to latitude, season, time of day, and weather. So one can construct a series standard reference model spectra, as seen here:
Unfortunately, only UV from 380nm to 400nm is shown here.

The link below compares natural sunlight (a "typical" day in Finland) with several reptile bulbs. The quality of the spectra seems high; I trust this data.
The entry link:
Specific page for spectra:

I will use this solar spectrum as my reference. I measured the approximate area of various zones of this spectrum. The total UV output (300nm-400nm) is ~9% that of PAR (the entire visual range, 400-700nm). The original author calculates 8.4% (but defines the visual range as 400-749nm), calculates 8.1% as UV-A (320-399nm), and 0.3% as UV-B (280-319nm). Absolute and relative UV output was tabulated for sunlight and reptile tubes here: 2.html

What is a reptile bulb? Many reptiles kept as pets suffer from a nutritional deficiency of Vitamin D; UV-B emited from reptile bulbs enables reptiles to photosynthesize Vitamin D (as in humans). Another type of reptile bulb is the heat lamp; this type is not being discussed here. Reptiles and birds can see into part of the UV-A range, UV-A is important for their physical and psychological health. I'm not going to bother hunting for links to bird lamps.

From the spectal figures and table, it can be seen that some reptile lamps, those with "8.0", "7%", or "5.0" appended to their trade name, have more UV output (in a relative sense) than the sun itself. Others in this class include the "Narva Reptilight" and the "Sylvania Reptistar". This enables the reptile owner to have a low electric bill. But plant people need much more visible light to drive photosynthesis (no low electric bills for us!), and the absolute UV intensity given off by an array of such lamps a few inches from plants, would probably too high for the plant (and even a human).

Other reptile lamps have a relative UV output similar to (or less than) the sun. I believe that the following would be OK as plant lamps: "ESU Super UV Daylight" (A GE Chroma 50 bulb with a little more UV thrown in?), "Hagen Life-Glo" (actually, an aquarium bulb), "Hagen Exo-Terra Repti-Glo 2.0" (just a relabeled "Life-Glo"), "Hagen Repti-Glo" (no real difference between previous two), or the "True-Light Daylight 6000". The last lamp is made in Finland and should not be confused with the "True-Lite" made in the USA.

The health aspects of such lamps for humans are discussed in the previous link; basically they concur with the comments by shrubs-n-bulbs a couple of posts ago.

Some more links;

Reptile photobiology:

A single fluorescent bulb is safer than sunlight:
(This doesn't compare the "super" reptile lamps)

More lamp data (absolute, not relative, values):

More spectra (CAREFUL, these are in log scale):

More tabular data (relative UV outputs):

To generate UV-A & UV-B, reptile (or human full spectrum) bulbs need special phosphors. I have not yet found any chemical info on these phosphors. I believe that "blacklights" use similar phosphors. All (?) fluorescent tubes may have a UV-A spike at ~375nm, I assume that this originates from excited mercury and not any phosphor (two additional mercury spikes are at ~420 & ~440; their location tells me whether the spectral curves have been redrawn correctly). To emit UV-C (254nm from excited mercury, eg., for a germicidal lamp), the fluorescent tube requires a special glass, normal glass absorbs 254nm. Using a germicidal lamps for plants is crazy, and is just mentioned here in passing. I conclude that it takes a whole lot of special effort to create a fluorescent lamp that posesses any great UV danger to plants.

My next post will cover aquarium fluorescents; metal halides after that.

RE: Lamps & UV isssues

I have read in the primary scientific literature that some of the red pigments are induced by UV (as a defense against UV); I don't have any references on hand.

I have observed that Lithops colouration (and other succulents, but I haven't so much experience) does not develop under warm white fluorescents, but does develop under standard 6500K (865) triphosphor bulbs.

RE: Lamps & UV isssues

This all comes down to Reptisun. Yes they have some value in plant stress assays. They can effect flavinoid and carotenoid production. Long story short is reduced flower and leaf mass, but 'unique' plants.

RE: Lamps & UV isssues - relabeled Aquarium

This post will look at aquarium fluorescent bulbs that are "normal" bulbs relabled for aquarium use. Next post will look at aquarium bulbs that are "special".

Some of these aquarium fluorescent bulbs are relabeled plant lamps, similar to the "Gro-Lux" or "Gro-Lux Wide Spectrum" from Sylvania (link reposted here):

Some that are similar to Gro-Lux narrow spectrum:
Hagen's "Aqua-Glo" (Hagen's claim of 18,000K seems strange)
GE's "Aqua Rays Freshwater" (has more yellow green than Gro-Lux)
[Aqua Rays Freshwater has some similarity to Osram or Narva "076" "meat display bulb>]

Some that are similar to Gro-Lux wide spectrum:
Hagen's "Flora-Glo"
Zoo Med's "Flora Sun"

Some are relabeled old fashioned general purpose halophosphor bulbs, Hagen's "Sun-Glo" seems equivalent to "Cool White"; while Zoo Med's Tropic Sun looks like a blend of "Cool White" and "Daylight" (Sylvania spectral link reposted here):

Some are relabeled full spectrum ("deluxe" phosphors). GE's "Spectra Rays Full-Spectrum" looks like GE's Chroma50. Coralife's "Colormax Freshwater Bulb" may fit in here somewhere.

Still others are run of the mill triphosphors (high kelvin triphosphors will be treated next post); compare with Sylvania's Octron 7xx and 8xx series:
Coralife "Nutri-Grow Plant Lamp"
Coralife "Trichomatic" 6500K
ATI "Sunpro"

Triphosphor with supplementation at 650nm (sort of a hybrid of Gro-Lux narrow spectrum [at 650nm] with triphosphor [611nm and below])
Arcadia "Plant Pro"
Arcadia "Tropical Sun" (more 650 than "Plant Pro)
Aquamedic's "Planta"

Some Links:

Foster & Smith has spectra that are sometimes absent (or difficult to see) at the "manufacturer's" web sites:

Coralife (see Foster & Smith for spectra; Coralife spectra are hard to read)

Hagen (most aquatic spectra are redrawn poorly, use Foster & Smith for spectra)

GE aquarium bulbs:


Aqua-Medic Medic T5 Bulbs


Zoo Med (if spectra are too small, try Foster & Smith)

In an aquarium forum, I have read that many aquarium bulbs are actually made in Germany by Narva (none of the above strongly match any Narva bulb):


None of the above seem to have any excessive UV output.

RE: Lamps & UV isssues - Flavor, Scent & UV-B

I wrote:
> I have read that UV increases the level of essential oils in mints & relatives...

This was in the popular literature on the web (& I don't recall the link). I wanted to find some primary scientific literature on the subject. The link cited below found that supplementation of greenhouse grown basil with UV-B increased the total content of essential oil. There was no change in the relative ratio of any essential oil component. Electron microscopy revealed corresonding changes in the essential oil glands that are found on the leaf surface. References to other papers about mint and another chemotype of basil are given.

The increased level of essential oil yielded a more powerful scent (and I assume flavor). The authors suggested that essential oils could act to absorb UV-B (a sunscreen for plants!). The classical role for essential oils is as a chemical warfare agent - the plant's defense against insects and disease. One could predict that increased levels of essential oil induced by UV-B could confer cross resistance against insects and fungi; ah... I will wait for a future post to discuss that.

The following link is to the abstract. The full paper is linked therein.

Here is a link that might be useful: UV-B increases basil scent

RE: Lamps & UV isssues - misc fluor stuff

Some corrections, comments & miscellanous links.

The link to Zoo Med is

I wrote:
> none of the above strongly match any Narva bulb
The ATI SunPro has some resemblence to the Narva "deluxe daylight 950"
This Narva lamp has a little "deluxe" phosphor [possibly (Sr,Mg)3(PO4)2:Sn] that modifies the red output of a triphosphor. Previously, I noted that the "AgroSun" compact fluorescents (up to 200W) looked a little strange in the red zone above the 611 spike (eg., at ~710nm). Normal triphosphors have a weak emission in this area, perhaps the AgroSun triphosphor is supplemented.

Narva has an interesting plant light, the "Lumoflor 077" which is similar to the Osram "Fluora 077". The Lumoflor has a broad red peak ~625 [possibly (Sr,Mg)3(PO4)2:Sn] while the Fluora has a narrow peak at ~650 [possibly Mg4(F)GeO6:Mn on top of a broad emission from (Sr,Mg)3(PO4)2:Sn]. Both somewhat resemble the GE "Plant & Aquarium Wide Spectrum" or Sylvania "Gro-Lux Wide Spectrum", except that the Lumoflor and Fluora have 1) less green output at ~525, 2) a lot more blue at ~450nm, and 3) possibly the blue phosphor has a faster decay in its output of UV-A.

One can look at a fluorescent spectrum, and guess what chemical types of phosphors were used for any given lamp, by going here:

Raw high resolution spectra of fluorescent bulbs have spikes at certain wavelengths. The green and orange-red components of triphosphor blends have very spikey output at ~550nm & ~611nm. Halophosphor and delux phosphor spectra are very smooth, with spikes resulting from mercury emission lines penetrating the glass and phosphor coating. The strongest mercury emission lines are: 254nm (UV-C, absorbed by glass tube), 297nm (UV-B), 365nm (UV-A), 405nm, 436nm, and 546nm. Note that the green mercury emission line is masked by the green output of triphosphors. I use the 405 & 436 lines to diagnose the quality of spectral plots. Blacklights, Tanning Lamps, Reptile and Full Spectrum bulbs for Humans that emit extra UV-A and UV-B do not rely on the small output from the 297nm and 365nm mercury lines; special phosphors are used.

A photograph of mercury emission lines:
A table of mercury emission lines:

Several aquarium web sites compile and compare fluorescent (and other lamp) spectral plots.
Dana Riddle:
Frank Greco:
Ivo Busko:

I have posted many links to quantitative graphs of spectra. A qualitative approach is to pass light through a prism and photograph the results. The following link takes such a holistic approach for fluorescent lamps with potential utility for aquariums (not all of the spectra are perfectly aligned, and the 405nm mercury emission spike seems to be missing):

Coming up: "Special" aquarium fluorescent and metal halide links.

RE: Lamps & UV isssues - Actinic Aquarium

Fluorescent Actinic Aquarium Bulbs:

I have seen the word "actinic" used in 3 senses: 1) a source of UV light, 2) a source of blue light, 3) in photosynthesis research, a source of bright light. In this post, actinic light is a nearly pure blue light, or a light source at the borderline of blue and near UV (UV-A).

In oceanic water that is relatively free of organics, blue penetrates further than red. Deep water corals don't see much red. People that have corals in their aquaria often use actinic lights to mimic the natural environment, and to observe brilliant fluorescent colors produced by some corals. Some corals have symbiotic dinoflagellate algae that provide much of their food. Dinoflagellate photosynthesis in nature and aquaria can be driven just fine with actinic light with very little contribution from red.

A very common actinic phosphor has a peak at 420nm, the peak quickly decays to ~380nm and ~480nm. This phosphor often has a code of "actinic 03". The UV output from 380 to 400 is ~1-2% of the total emission as estimated from the spectral graph for the Zoo Med "Coral Sun Actinic 420" lamp and ~9-10% for the URI "Actinic 03" (spectral graphs from Foster & Smith). I don't think that this represents a real difference between the lamps. Rather, the blue output is so close to the UV, that small errors in redrawing the spectral plot (in relation to the wavelength tick marks), can alter the apparent UV level. In any case, the character of this UV content is closer to blue light than to typical UV-A light, and I don't consider it to be dangerous even if it does represent 10% of the total. Spikes from mercury emission are also present.

Some links to pure Actinic 03 lamps:
Zoo Med Coral Sun Actinic 420
URI Actinic 03
Coralife Actinic 03 Blue
Coralife Magtinic
Hagen Marine-Glo
Aqua Medic Ocean Blue 20,000K (a T5) Medic T5 Bulbs
AquaZ Blue Pro (a T5)
ATI Actinic Blue (a T5)

The Arcadia "Marine Blue Actinic" lamp has a peak ~420 but seems to have a little more UV. Perhaps a UV phosphor was added or the plot was redrawn so small that it is no longer accurate:
Likewise for the Current "Sun Paq 420nm Actinic"

Another common actinic phosphor has a peak ~450nm, which decays to 400nm and slowly decays to 525nm. The UV output is very small. This phosphor(s) may just be the blue component of the common triphosphor mixes. Spikes from mercury emission are also present. Some examples:
ATI Blue Plus
Narva 0182
Current "SunPaq 460nm Actinic"
Interlectric "BiliBlue" (a medical lamp, could be used in aquaria)

There is a third "blue" lamp, with a peak ~400nm which slowly decays to 300nm and 650nm. About 1/3 to 1/2 of the output is UV. The prototype is the GE "Saltwater" bulb coded as "AR/SA"
Interlectric "Blue"

Similar high UV blue lamps, with a peak ~425
Interpet "Blue Moon"
Narva "Blue 018"

I think that this third class of blue lamps have too much UV as a plant lamp (if used by themselves). If you want to add a little UV to your plants, you could use them to supplement other bulbs.

Note: some of the spectra in the Current "SunPaq" pdf document are shifted ~100nm from their true values.
Coming soon: high Kelvin bluish/white aquarium bulbs.

RE: Lamps & UV isssues

Here's someone growing seedlings under a lizard lamp, for a little while at least. You might want to query him on which one and how strong.

Here is a link that might be useful: Lizard light (about the either reply)

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