# UV STOP good or bad?



## IRXMJ (Dec 31, 2009)

Today I purchased a 150 W MH fixture + bulb of following manufacturer and model:

SYLVANIA METALARC HSI-TD 150 W

It says "UV STOP".  Does this mean the good MH light is blocked and thus non-effective as grow light?

Does anyone know?  Please advise.  If no good, I would like to return and exchange for a better bulb.


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## leafminer (Dec 31, 2009)

No. It means that the lamp does not emit dangerous levels of UV.


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## IRXMJ (Dec 31, 2009)

leafminer said:
			
		

> No. It means that the lamp does not emit dangerous levels of UV.



Thanks for answer.  Do you mean "No" to some question and that it is YES still good use for growth?  I hope so, because this light has cool swivel so I can hang it if I drill it into wall or board, or use as "leg" on which to lean ala picture frames that "stand" on table.


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## DonJones (Jan 1, 2010)

IRXMJ.ORG,

If you are going to grow medical marijuana for others, then you need to study and study until you understand what you're doing rather than just stumbling around until you get lucky.  Those people are depending on you to get it right the first time and every time.

Start with reading the stickys in the front of this section.  Especially the ones that show what spectrum plants use and what kind of lights give off what kind of spectrum.

Getting back to your original, question, UV = Ultra Violet light.  UV is harmful to virtually every beneficial life form.  So while a UV filtered light is going to loose some good light, that is going be by far overshadowed by protecting your plants and the entire environment fro the harmful UV spectrum.

While, hesitate to challenge anyone's representations of them self, I must say your signature doesn't ring true with your question and what it reveals about you.  You will find that the worst thing you can do here on this forum is to try to portray yourself as more knowledgeable or "better" than you actually are.  Humility and a willingness to admit your real status will get you farther than anything you can do on this forum.  Don't bother trying to impress anyone, because the ones who count will quickly see what you really are, regardless of whether you over sell or under sell yourself, as well as not caring anyway, and the rest of them are too busy trying to impress each other to care about who and what you are.

If I have misread they meaning behind your signature, then I apologize but Even your nick name reeks of an attempt to impress us and it will NOT work.

Good smoking! and good luck because anyone who is actually wanting to help sick people through the use of MJ is someone that is worth helping.


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## BBFan (Jan 1, 2010)

DonJones said:
			
		

> IRXMJ.ORG,
> While, hesitate to challenge anyone's representations of them self, I must say your signature doesn't ring true with your question and what it reveals about you. You will find that the worst thing you can do here on this forum is to try to portray yourself as more knowledgeable or "better" than you actually are. Humility and a willingness to admit your real status will get you farther than anything you can do on this forum. Don't bother trying to impress anyone, because the ones who count will quickly see what you really are, regardless of whether you over sell or under sell yourself, as well as not caring anyway, and the rest of them are too busy trying to impress each other to care about who and what you are.


 
DonJones-

That's a pretty harsh statement (not only to the OP, but to many other posters here on MP). Was it necessary to attack him? Ultimately, does it really matter who he or she claims to be? He/she is merely asking a question.



			
				DonJones said:
			
		

> Getting back to your original, question, *UV = Ultra Violet light. UV is harmful to virtually every beneficial life form*. So while a UV filtered light is going to loose some good light, that is going be by far overshadowed by protecting your plants and the entire environment fro the harmful UV spectrum.


 
You are absolutely incorrect in this statement. If you read and research (as you advised the OP), you will find that UV light, specifically UVB, is actually beneficial to some growth. Also, much of the UVB spectrum is actually within the absorbtion spectra of certain photosynthetic pigments.

Many growers, myself included, actually introduce UVB lighting to their grows with beneficial results. Robert Clarke, a noted botanist, in his book, _Marijuana Botany_, discusses the benefits of UV and it's impact on trichome production as well as it's benefits in converting certain precursers to THC (such as THCA) into THC. This is not my opinion, it is based on the research of others. I can provide you with resources if you wish to research further.

Sorry if I come across harsh but I find your attack distasteful and unwarranted.


IRXMJ.ORG-

The UV output of a MH bulb is nominal, particularly in such a low wattage bulb. The glass around the bulb itself diminishes the UV output to a degree (just as a window does). Certain bulbs come with an additional glass jacket that further reduces UV output. Personally, I wouldn't use it for growing, but I don't know if the impact is that significant.

As I stated above, some UV lighting has been shown to be beneficial to growth.  Good luck and Happy Growing!


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## HippyInEngland (Jan 1, 2010)

Hello IRXMJ.ORG 

Ask as many questions as you need to learn, we will all help 

DJ.

Your post was rather harsh, what does this mean?



			
				DonJones said:
			
		

> *Don't bother trying to impress anyone*, because the ones who count will quickly see what you really are, regardless of whether you over sell or under sell yourself, as well as not caring anyway, and *the rest of them are too busy trying to impress each* *other* to care about who and what you are.


 
:confused2: 

eace:


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## Mutt (Jan 1, 2010)

I agree that was harsh. Dude just asked what the UVstop meant.


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## IRXMJ (Jan 1, 2010)

BBFan said:
			
		

> Sorry if I come across harsh but I find your attack distasteful and unwarranted.



No need for *you* to apologize.  You are correct the attack was distasteful and unwarranted.  Thanks for the other voices to defend against flaming which seems common at these forums/groups/boards, which is why I have avoided ever registering.

Don Jones, considering that all Rx Medical Marijuana is grown by volunteer growers of their own good will, and as it is given free to all license-holders patients who receive, I think your words are doubly-unnecessarily harsh.  I am not selling the marijuana; I am investing my own time, money in growing in order to give it away for free.  

If, in my effort to improve the quality of the medical marijuana I produce I ask questions to learn more, if I am attacked here by such as you, why should I ask and risk being flamed by hyper/over-active zealous members of forums & boards like this?


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## IRXMJ (Jan 1, 2010)

I am still not certain what answer is:  is this UV Stop bad for growing?  Is it totally worthless like a halogen?  or is there grow benefit of MH?


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## HippyInEngland (Jan 1, 2010)

The UV block will allow you to grow but will not harm your skin or eyes.

eace:


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## leafminer (Jan 1, 2010)

All HID lamps are provided with a glass envelope that reduces the emission of harmful UV radiation. HPS bulbs specifically have a warning on the box that states not to use the bulb if the outer glass is broken. The outer glass does not affect the lamp's ability to grow. I hope that is clear?


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## Icex420 (Jan 1, 2010)

HippyInEngland said:
			
		

> The UV block will allow you to grow but will not harm your skin or eyes.
> 
> eace:


 
Ah hippy, who told you this?  

If you stare at any light bulb, it will burn the retina's out of your eyes, depending on how long you stare.

Even quick accidental glances over time are detrimental to you're vision.

RX- Youre light is fine. GL


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## IRXMJ (Jan 2, 2010)

Thank you very much to you 3.

You have broadened my horizons and my thinking about my light set up.  I have have one 400 W MH that over the hears the plastic has melted off so some of the "raw light" is exposed.  That bulb I don't remember specified UV Stop - so many there is harmful radiation?

The new lamp sounds good from what you guys say.  It is also really bright light, much "whiter" than the 400 W MH which is more yellow.  Together they really place lots of sunshine light all around my plants.

I am wondering of the glimpses I get into these lights are going to really damage my vision with each glimpse?


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## OldHippieChick (Jan 2, 2010)

Sorry,  I posted in the wrong thread....


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## Icex420 (Jan 2, 2010)

Icex420 said:
			
		

> Even quick accidental glances over time are detrimental to you're vision.


 
Yes. Some people use sunglasses when they enter the growroom.


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## dirtyolsouth (Jan 2, 2010)

Geeeeez...

I guess the holiday season is over DJ?:hubba:  Maybe we all need to do LOTS of "Good Smoking" to get our melons gellin' in 2010....


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## DonJones (Jan 4, 2010)

dirtyolsouth,

I agree that we all need to mellow out.  Yes I'm a harsh direct speaking person.  I'm never claimed to be a diplomat, but maybe you all should reread the last two sentences of my harsh post before you start becoming harsh yourself. to make it easier, here they are again.

*If I have misread they meaning behind your signature, then I apologize but Even your nick name reeks of an attempt to impress us and it will NOT work.

Good smoking! and good luck because anyone who is actually wanting to help sick people through the use of MJ is someone that is worth helping.*

I don't know how to make it any plainer of humbler that to admit that I may have misread him and to apologize if that's the case.  Nor do I know how to make it any plainer that if he is who he claims to be, then he is some one to be helped, and I should have added to be admired.

I notice though that he doesn't object to my characterization of the impression he gave me nor does he try to correct me.  But there are sure a lot of you who can't wait to become harsh too.

I stand by my original post.  And everything I said in there applies to me too.  If I'm going to try to provide medicinal marijuana to patients, I need to get it right every time because they are depending on me.  When we start providing medicine of any sort to other people we have no room for errors or experiments.

If I am wrong about him, then he already has my apology and I am open to being corrected.  If I'm right or even some where in between the advice I gave him is good advice.  If he already knows what I offered then it doesn't apply to him and if doesn't already know it but chooses to disregard it,that is okay too.

Great smoking to every one.  RX, if I'm wrong, please tell me so and like I already said, I apologize if I'm wrong.

And please do NOT for a minute think that I know every thing or haven't learned a lot and eaten a lot of humble pie, even here on the forum, as well as throughout my life.


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## DonJones (Jan 4, 2010)

RX,

My apology to you still stands.  It won't be either the first or the last time i am wrong.

Nor is you pat me on the back stuff about growing the MJ to give it away relevant to the discussion.  No where did I mention selling or giving it away.  Nor does the gifting or selling of the MJ change our responsibility to our patient to get it right EVERY TIME.  I too give medical MJ to those who can't grow it or can't afford to buy it, but the ones who can afford it on their lifestyles, I charge for it to help offset the production cost of those who can't afford it.  Does than make me special or a good guy? -- absolutely NOT.


Greatr smoking and may you become the best most productive mj grower in the world and help the multitudes, because the world needs all the help it can get in easing the pain and suffering of the people, even from the small contribution that an oaf like myself can give.  May GOD bless you and your country!


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## DonJones (Jan 4, 2010)

BBFan,

I'm still checking your source.  and while some limited bands of the UV spectrum may have beneficial effects in limited circumstances, the fact remains that UV in general is generally considered to be very harmful to most forms of life.  If you will reread my statement, it was qualified* (virtually) *rather than a blanket statement for every particular band of UV and in every circumstance.

After all it is often the last sterilization technique before hard radiation for surgical instruments.

Good smoking and thank you for at least offering some sources for me to research.


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## leafminer (Jan 4, 2010)

The problem with discussing UV, for me, has always been the issue of what the resin production is for (from the plant's point of view I mean). If it is - as some say - to protect against UV, then it would make sense to blast the plants with UV. But UVA or B ??? 
But that may be completely wrong. Another theory states that the plant produces the resin to get predators stoned so as to forget where they found the plant...
And yet another theory states that the sticky trichs act to catch insects or stop insects attacking ...
For me the problem is that I would "like" to test these theories but my personal requirements (getting some smoking material) get in the way.


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## DonJones (Jan 4, 2010)

Amen to the smoking getting in the way! 

 Your comments about the purpose of the plant making resins and/or trichs is dead on --  Just because we are looking for resin and trichs and blasting the plant with UV, regardless of the spectrum, does NOT necessarily mean that UV is NOT harmful to the plant.  

There are people who would make the same arguments about tapping rubber trees or maple trees but the fact remains that tapping both of those trees causes the tree to try and heal itself by secreting sap to heal the damage to the tree.  There fore just because we are collecting the sap from the tree and getting what we want from the tree does NOT make tapping it good for the tree.  It is widely known and universally accepted that over tapping a tree will eventually kill it, not just weaken it. 

Great smoking man.


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## Mutt (Jan 4, 2010)

I've read a theory that the crystals are to protect the plant. One grower said the desert grow of the same exact strain was frostier then in SoCal where it was a lil more humid. Which in a way would make sense as the resin would slow transpiration.


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## BBFan (Jan 5, 2010)

I've done a lot of reading and researching on UVB an it's affects on our plants.

DonJones is correct in saying that UV hurts living organisms- just not all UV.  Some UV light is actually within the action response spectrum for photosynthesis in plants.  And, by the way, UVB is what causes our bodies to produce vitamin D.

But, while I'm hard pressed to find documented and scientifically verifiable results regarding UVB use (not UVA or UVC) and it's affects on trichomes and THC production (thank you _DirtyOlSouth_ for pushing me in that direction!), there is still alot of info out there from respectable sources that make it worth a second look.

What I've read is that UVB causes a stress which causes our girls to produce trichomes as a defense mechanism.

I've also read that UVB helps turn certain cannibinols and acids in our trichs into THC.

I've only just completed my first grow with supplemented UVB lighting.  I'm not at the point where I'm doing double blinds, but anecdotal responses and my personal observations have been very encouraging.  My son says I could sell it for $50.00 a gram.  All I know is one hit and I'm in lala land.  Excellent for when I need to get some sleep.

(Note- I don't sell what I grow.  Ever.  I give most of my grows away as I don't need much.  I seek my son's opinion as he has a lot of friends "in the business"- and he always takes the most anyway - though I've been cheap on giving him the plant that got the UVB light.)

I have saved much of the data I've found and would be more than happy to share with anyone interested!


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## IRXMJ (Jan 8, 2010)

Mutt said:
			
		

> I've read a theory that the crystals are to protect the plant. One grower said the desert grow of the same exact strain was frostier then in SoCal where it was a lil more humid. Which in a way would make sense as the resin would slow transpiration.



I agree with this.  When I grow outdoors in hot Israel Spring/Summer and/or my grow rooms are hotter in Autumn & Spring, the trich production is much more pronounced.


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## IRXMJ (Jan 8, 2010)

BBFan said:
			
		

> I've done a lot of reading and researching on UVB an it's affects on our plants.
> 
> DonJones is correct in saying that UV hurts living organisms- just not all UV.  Some UV light is actually within the action response spectrum for photosynthesis in plants.  And, by the way, UVB is what causes our bodies to produce vitamin D.
> 
> ...



I 'd be interested!  Please share your info/experience with me!


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## DonJones (Jan 9, 2010)

BBFan,

While I would like to review your information, especially in a separate thread where we wouldn't have to try to sift through the other issues here or a PM, I am even more interested at the moment in knowing how you supplement the UVB without increasing the UVA and UVC.  

You said, I think, that UVB was what caused our bodies to produce vitamin D, which could very well be true since it has long been published that exposure to sunlight is what causes the production.  What I don't understand is why sunblock lotions/creams list protection factors against both UVA and UVB.  Also, I haven't noticed any ratings on UVC.  Any explanations would be appreciated.

Incidentally, most medical treatments involve using something that is basically harmful in uncontrolled circumstances to harm an unhealthy condition more than what it does the healthy condition to achieve an overall improvement in health.  Does that sound as confusing to you guys and gals as it does to me?  I sure hope not.  Hopefully you will understand what I meant because I sure didn't make it sound like I wanted it but I can't think of a better way to say it right now.

Great smoking and happy 2010.


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## BBFan (Jan 10, 2010)

IRXMJ said:
			
		

> I 'd be interested! Please share your info/experience with me!



Hi IRXMJ!

Hope all is well with and for you.  I will post some info at the end of this post.  There's plenty more where that came from, and some of it can be quite tedious.  I'll be happy to share as much as you want.  Let me know.

But first I would like to respond to DonJones' post.



			
				DonJones said:
			
		

> I am even more interested at the moment in knowing how you supplement the UVB without increasing the UVA and UVC.



Hello Don!

I am introducing UVB to my plants via a self ballasted mercury vapor lamp.  These lamps are readily available from pet supply companies.  Before I settled on the Zoo Med lamp, I looked at the output and efficacy of the different lamps that are readily available to the general public, specifically for reptile health and breeding.

I don't think any of them produced UVC wavelengths, but did produce both UVA and UVB.  UVC from the sun never reaches the earth as it is absorbed in the earth's atmosphere, that's why you don't need sunblock for it.

I'd like to clarify an earlier statement I made regarding UVB wavelengths and whether they are harmful.  I was referring to a small portion of the UVB spectrum in that statement.  In large doses, I think most UVB is harmful.



			
				DonJones said:
			
		

> Incidentally, most medical treatments involve using something that is basically harmful in uncontrolled circumstances to harm an unhealthy condition more than what it does the healthy condition to achieve an overall improvement in health. Does that sound as confusing to you guys and gals as it does to me? I sure hope not. Hopefully you will understand what I meant because I sure didn't make it sound like I wanted it but I can't think of a better way to say it right now.



I think I get what you're saying.  Kind of like chemotherapy and radiation therapy used in the treatment of certain cancers.  Both of these treatments kill good cells, but the benefits of destroying the bad cells outweighs the destruction of the good cells.

Same thing, based on what I've read, regarding UVB and it's effects on our plants.  MJ (and other plants) produce trichomes to protect against cellular damage from UVB.  It is a defense mechanism.  But the end result is better for us (maybe not so the plant  ).

Also, if you read and believe the following article but Joe Knuc, the result is also more potent THC.

Happy smoking to you too.


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## BBFan (Jan 10, 2010)

Here is a short article I found regarding UVB and it's effects on MJ plants.  The source I found credited Joe Knuc as the author.



> An elaboration on the phytochemical process that makes THC
> By Joe Knuc
> 
> "Pate (1983) indicated that in areas of high ultraviolet radiation exposure, the UVB (280-320 nm) absorption properties of THC may have conferred an evolutionary advantage to Cannabis capable of greater production of this compound from biogenetic precursor CBD. The extent to which this production is also influenced by environmental UVB has also been experimentally determined by Lydon et al. (1987)."
> ...


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## BBFan (Jan 10, 2010)

Here is an excerpt from R.C. Clarke in his book "_Marijuana Botany_".



> Conversion of CBD acid to THC acid is the single most important reaction with respect to psychoactivity in the entire pathway and the one about which we know the most. Personal communication with Raphael Mechoulam has centered around the role of ultraviolet light in the bio-synthesis of THC acids and minor cannabinoids. In the laboratory, Mechoulam has converted CBD acid to THC acids by exposing a solution of CBD acid in n-hexane to ultraviolet light of 235-285 nm. for up to 48 hours. This reaction uses atmospheric oxygen molecules (02) and is irreversible; however, the yield of the conversion is only about 15% THC acid, and some of the products formed in the laboratory experiment do not occur in living specimens. Four types of isomers or slight variations of THC acids (THCA) exist. Both Delta1-THCA and Delta6-THCA are naturally occurring isomers of THCA resulting from the positions of the double bond on carbon 1 or carbon 6 of the geraniol portion of the molecule They have approximately the same psychoactive effect; however, Delta1-THC acid is about four times more prevalent than Delta6-THC acid in most strains. Also Alpha and Beta forms of Delta1-THC acid and Delta6-THC acid exist as a result of the juxtaposition of the hydrogen (H) and the carboxyl (COOH) groups on the olivetolic acid portion of the molecule It is suspected that the psychoactivity of the a and ~ forms of the THC acid molecules probably does not vary, but this has not been proven. Subtle differences in psychoactivity not detected in animals by laboratory instruments, but often discussed by marijuana aficionados, could be attributed to additional synergistic effects of the four isomers of THC acid. Total psycho-activity is attributed to the ratios of the primary cannabinoids of CBC, CBD, THC and CBN; the ratios of methyl, propyl, and pentyl homologs of these cannabinoids; and the isomeric variations of each of these cannabinoids. Myriad subtle combinations are sure to exist. Also, terpenoid and other aromatic compounds might suppress or potentiate the effects of THCs.
> 
> Environmental conditions influence cannabinoid biosynthesis by modifying enzymatic systems and the resultant potency of Cannabis. High altitude environments are often more arid and exposed to more intense sunlight than lower environments. Recent studies by Mobarak et al. (1978) of Cannabis grown in Afghanistan at 1,300 meters (4,350 feet) elevation show that significantly more propyl cannabinoids are formed than the respective pentyl homo-logs. Other strains from this area of Asia have also exhibited the presence of propyl cannabinoids, but it cannot be discounted that altitude might influence which path of cannabinoid biosynthesis is favored. Aridity favors resin production and total cannabinoid production; however, it is unknown whether arid conditions promote THC production specifically. It is suspected that increased ultraviolet radiation might affect cannabinoid production directly. Ultra-violet light participates in the biosynthesis of THC acids from CBD acids, the conversion of CBC acids to CCY acids, and the conversion of CBD acids to CBS acids. However, it is unknown whether increased ultraviolet light might shift cannabinoid synthesis from pentyl to propyl pathways or influence the production of THC acid or CBC acid instead of CBD acid.


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## DonJones (Jan 10, 2010)

BBFan,

Your example of chemotherapy and/or radiation is exactly what I was thinking of only I was thinking more along the idea of antibiotics, which isn't quite as clear as your example.

You finally showed me a use for MV lights in growing!  I had never heard of them being good for anything in growing before, but I thought there must one somewhere.


Okay, now for the nitty gritty -- How much do you use and in what combination with HPS?

Do I need to have a light for each large plant like I use my HPS 400s or does it diffuse enough to just hang one high in the general center of the area?

My active flowering area in the room is approximately 6' x6' with an occasional enlargement up to 6' x8'.  I currently run 3 HPS 400s and have an additional 4 MH 400s that I can use if needed.  I'm in the process of acquiring more HPS with a goal of 6 HPS 400s for use and an additional one for reserve in case of a failure of one of the primary ones.

Do you have any quantitative information on the difference it makes or mostly just subjective impressions?  I'm very aware that the "objective hard data" is not too likely to be within the means of most growers, but I've been surprised before at what some growers have access to.

Getting back to the original question on the post, (a) of the first quote *"(a)Examples of an environment where the UVB photon would be missing from the light stream include all indoor cultivation illuminated by HID bulbs and in glass or corrugated fiberglass covered greenhouses"* seems to imply that the UV spectrum of MH & HPS lights is so slight that it isn't going to make any difference to a grow operation whether it is filtered out or not.

The second quote from Clarke doesn't seem to help much from a practical standpoint, but IO guess maybe understanding it might help to understand something more practical later.

Thanks for the information.  I'm always grateful for any way to improve my yield, which to me means the active ingredients not just the volume/weight of the bud I get.

Great smoking.


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## BBFan (Jan 11, 2010)

DonJones said:
			
		

> You finally showed me *a use for MV lights in growing*! I had never heard of them being good for anything in growing before, but I thought there must one somewhere.
> 
> 
> Okay, now for the nitty gritty -- How much do you use and in what combination with HPS?
> ...


 
DonJones-

Please understand, I am not advocating the use of mercury vapor lights for your space. IMO, about the only thing they're good for is producing heat. However, the light I use is an _enhanced mercury vapor_ bulb that provides some light in the UVB spectrum. It is specifically labeled and sold as such. Even the bulb I used generated heat which was a constant battle. UVB lights are also available in flouros, perhaps that would better suit your needs.

As far as quantitative data, I cannot provide any. I have more research if you're interested in further reading- but nowhere is there any definitive or quantifiable information regarding results. I can only offer what I have read and my own observations, which I stated were inconclusive. My own experience in using the uvb was aimed at one plant to compare to the others grown under otherwise same conditions. I introduced the uvb while the plants were in veg at about 1 hour a day and continued exposure up through flowering to a maximum of about 6 hours a day.

_DirtyOlSouth_ is someone who really pushed me to experiment with UVB lighting. I don't believe he has any specific data either, but he does offer personal anecdotal information which may be of some value to you in your research. Without gas chromatography or some other method to measure THC content, I don't know that I could ever provide more than an opinion. I am not a scientist, I only play one on TV and here at MP  .

My research has shown that MH produces more wavelengths in the UV spectrum. But this is again something that is not commonly or readily available beyond the occassional warning labels that come with the bulb.

All of this, from my understanding, points to improved thc content and potentiation; nothing about improved yield.

Probably the best anecdotal evidence would come from someone who grows the same cuts both indoor and outdoors- though I beleieve I am dosing my plants more than an outdoor grower in northern latitudes would receive. I no longer grow outdoors and have nothing to use for comparison.

Happy Smoking to you too!


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## DonJones (Jan 11, 2010)

BBFan,

Damn, here you go and get me all excited and then tell me you don't have any idea how much to use or how much good it does.

In YOUR opinion, does it seem to help if the plants are vegged under MH or do they seem to have enough UV without it?

What does anyone know about supplementing the HPS with MH, like how much and does it need o9t be the same ration for each plant or can I just hang a couple of MHs near the center area of the room and let it spread out?

Sorry to get off track.  

*BBFan, I'm just dissapointed, and not with you.*

Great smoking.


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