# UV B to increase THC



## Puffin Afatty (May 7, 2008)

_ Howdy Grow Folks!!!_

_:hubba: I have been interested in trying UV B to increase the conversion of thc in the resin heads.  Have any of you tried this, and if so, what regimens?? _


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## Runbyhemp (May 7, 2008)

Have to plead ignorance on this one Puffin. Care to elaborate a little bit?


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## Puffin Afatty (May 7, 2008)

Runbyhemp said:
			
		

> Have to plead ignorance on this one Puffin. Care to elaborate a little bit?


 
:hubba: I_ saw a video on youtube. [youtube.com/watch?v=IPcpt3Be28o]  discussing the merits of UV B on pot plants indoors.  I had been previously reading about it on OG for a while and even got a couple exo terra reptiglo 10.0 UVB Bulbs.  I am gonna start dosing SnowWhite with them again._


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## GreenMan74 (May 7, 2008)

I've read about this too.  I think it had something to do with the speculated reason why MH produces a higher potency bud.  Can't recall.  But it looks sound.


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## Puffin Afatty (May 8, 2008)

GreenMan74 said:
			
		

> I've read about this too. I think it had something to do with the speculated reason why MH produces a higher potency bud. Can't recall. But it looks sound.


 
_ I hadnt recalled the MH issue, but it seems  that added UV B increases the conversion of cbd's to thc.  I am gonna try it on SnowWhite and see if I can get the trichs to go amber earlier than 14 weeks:hubba: _


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## massproducer (May 8, 2008)

Puffin this was a very good little documentary.  It all seems to make sense to me.  I love how Mr.Green goes into the scientific aspect of THC production.  

K+


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## Puffin Afatty (May 11, 2008)

massproducer said:
			
		

> Puffin this was a very good little documentary. It all seems to make sense to me. I love how Mr.Green goes into the scientific aspect of THC production.
> 
> K+


 
Yes, I thought it good as well.  HippyinEngland was the one who tipped me to it 1st. 

:farm: I know the UV B will kill the mildew, and I kinda think it would also distress the mites, thrips, knats, etc., eh??  perhaps there is more to this UV B than meets the eye, eh? :rofl:


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## Brouli (May 11, 2008)

agreeeed  UVB stop's mold, and helps THC   i have a little talk witm my friend in Amsterdam and and they all use UVB bubs in addition to HPS .




Caution:
UVB can couse skin cancer ,always turn lights off when u enter just for safety. (u just spending there few minutes would not harm u but in a long run it may)


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## Puffin Afatty (May 11, 2008)

brouli said:
			
		

> agreeeed UVB stop's mold, and helps THC i have a little talk witm my friend in Amsterdam and and they all use UVB bubs in addition to HPS .
> Caution:
> UVB can couse skin cancer ,always turn lights off when u enter just for safety. (u just spending there few minutes would not harm u but in a long run it may)


 
_:hubba: Thanks Brouli!!!_

_I know the mold is killed by UV B, and It would be nice to get rid of the NSP's._


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## Cole (May 11, 2008)

You should make a UV B/HPS Grow journel.


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## IllusionalFate (May 11, 2008)

How is UV A for growing compared to UV B?


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## Cole (May 11, 2008)

Whats the difference?


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## IllusionalFate (May 11, 2008)

Different Kelvin spectrums. I think UV A is around 10k.


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## AlBundy (May 13, 2008)

Be careful with the UV-B, it can "burn" your girls.  At least that is my experience.  I need to find a way to moderate the amount of UV-B as my grow area is very small.


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## bombbudpuffa (May 13, 2008)

UVA 400 nm - 320 nm
UVB 320 nm - 290 nm
UVC 290 nm - 100 nm


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## liermam (May 14, 2008)

As far as I know, the progression in trichomes goes from THC-> CBD as the harvest window passes. I really don't understand how the exact opposite could happen...


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## Brouli (May 14, 2008)

its not uvb  reys that burn ur plat but light itself u got it too cloes, this is the video that every one should watch wo is interested in uvb and what can i t do for as.

http://youtube.com/watch?v=IPcpt3Be28o


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## DaveTheDingo (May 20, 2008)

Everyone i've talked to says "get UVB in there" - There's a lot of evidence that UVB helps plants, working on the variance in UVB concentration in different parts of the world. Those reptiglo bulbs seem to me to be a good idea, they shouldn't be too harsh being designed for lizards - going to use one myself from day 1 in flowering


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## Brouli (Aug 19, 2009)

puffin im curies have u had any good results ???
i think it helps with amount of produced thc i v been using it hard and crystals look bigger and its way more of them ,when i get back to US i will post some pics .


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## HippyInEngland (Aug 19, 2009)

Welcome back Brouli 

Puffin hasnt been seen for over 9 months.

Last Activity: 12-11-2008 08:02 PM 

1 of his last posts was him saying he had flu.

He hasnt been seen on any of his other regular forums either for the same amount of time.

eace:


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## tcbud (Aug 19, 2009)

Dang HIE, I wondered bout Puffin too....where he went...Hope all is well with him...


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## meds4me (Aug 19, 2009)

massproducer said:
			
		

> Puffin this was a very good little documentary. It all seems to make sense to me. I love how Mr.Green goes into the scientific aspect of THC production.
> 
> K+


 

***Mass I want youre opion on this matter too claify a few things for me. As I understand it Metal halides and the light spectrum they produce is better for veg'ing a plant. HPS, on the other hand , being a red spectrum bulb produces a better suited light source for flowering.


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## meds4me (Aug 19, 2009)

Somehhere i had read that UofW had done a research had proved a less than 10% diff ( in favor of HPS) between the 2 light sources for flowering. Or am I wrong...


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## BBFan (Aug 19, 2009)

meds4me said:
			
		

> Somehhere i had read that UofW had done a research had proved a less than 10% diff ( in favor of HPS) between the 2 light sources for flowering. Or am I wrong...


 
I've read that MH, while producing slightly smaller flowers, produces more trichomes on your flowers.

I'm running an experimental grow right now where I am introducing UVB lighting to the grow and intend to finish out the last 2 weeks with MH.

We'll see.


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## dirtyolsouth (Aug 20, 2009)

Tons of info here and elsewhere so you can draw your own conclusions....  

If you use Google's 'advanced search' and tell it to search for 'UVB' within 'marijuanapassion.com' domain you get all this:

Paste this web address into your browser and replace the XX with tt...

hXXp://www.marijuanapassion.com/forum/archive/index.php/t-39358.html


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## Brouli (Aug 29, 2009)

Hi Hippie how u doing those days?? hope green  nice to be remebered


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## LEFTHAND (Aug 29, 2009)

BBFan said:
			
		

> I've read that MH, while producing slightly smaller flowers, produces more trichomes on your flowers.
> 
> I'm running an experimental grow right now where I am introducing UVB lighting to the grow and intend to finish out the last 2 weeks with MH.
> 
> We'll see.


 
hey bbfan
how are you introducing it??
i imagne you started off on small incerments??
i would say by half way through your grow you should be having it on 4+ hrs to create  "high noon" this would be after the plant has built a better tolorence to the uvb lighting..
is the last 2 weeks gonna be enough time to make a diference in growth?? or just a waste of time?
i think one would have better success if he had blue red and uvb lighting in there at once to me that would be like sitting out in the sun on a nice summer day..
i have never done this bfore but read tons on it.. except the MH for flowering, i say thats just poppy cock. 
LH


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## BBFan (Aug 29, 2009)

LEFTHAND said:
			
		

> hey bbfan
> how are you introducing it??
> i imagne you started off on small incerments??
> i would say by half way through your grow you should be having it on 4+ hrs to create "high noon" this would be after the plant has built a better tolorence to the uvb lighting..
> ...


 
Hi Lefthand-
Plants are only 4 weeks old and I just flipped to 12/12 a week ago. I just started introducing the uvb yesterday (I had some nute burn issues to resolve first). Starting with 1/2 hour a day and hope to get to 4 hours by week 6 of flower. We'll see how they do. Otherwise the plants are still under a Sunmaster cool deluxe MH with supplemental hps side lighting.

Not sure what you mean by the mh for flowering. Everything I've read says it produces more trich's than hps, that's why I will switch back to the mh for the last 2 weeks.

Week 1 MH with supplemental HPS side lighting
Week 2-3 MH, supplemental hps, introduce uvb
week 3-8 HPS, supplemental hps uvb to 4 hours/day
week 8-Finish MH, supplemental hps, uvb at 4 hours

That's the schedule I'm going with. Plants haven't even sexed yet.

I still have a jar of nugs from this strain from a grow I did a little over a year ago. That'll be the only thing I will be comparing to. Completely subjective testing, but I grow for myself and a few friens only, so if we're happy, that's good enough.


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## LEFTHAND (Aug 29, 2009)

BBFan said:
			
		

> Hi Lefthand-
> Plants are only 4 weeks old and I just flipped to 12/12 a week ago. I just started introducing the uvb yesterday (I had some nute burn issues to resolve first). Starting with 1/2 hour a day and hope to get to 4 hours by week 6 of flower. We'll see how they do. Otherwise the plants are still under a Sunmaster cool deluxe MH with supplemental hps side lighting.
> 
> Not sure what you mean by the mh for flowering. Everything I've read says it produces more trich's than hps, that's why I will switch back to the mh for the last 2 weeks.
> ...


 
thats what counts.. yourself.. lol but hmmm thats a neat lil light schedule, i myself yet to try but i wanna get through my first legit grow first.. i use fluorecents for my bigger veg in my tent.. well will be still yet to do so,4 sets of 2 T12's 4' long hope it wrks , im sure a MH will do much better for penatration but my power bill wont like it.. ive never used MH b4 either lol.. well hopefully you keep us posted.. im intrested to see what happens..
LH 
HAPPY GROWING


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## classic_rocker_287 (Sep 7, 2009)

what would be wrong with UVB on 12\12 with a 400 HPS? I mean do you have to introduce it slowly cause I just put mine on my timer and left it.


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## BBFan (Sep 8, 2009)

classic_rocker_287 said:
			
		

> what would be wrong with UVB on 12\12 with a 400 HPS? I mean do you have to introduce it slowly cause I just put mine on my timer and left it.


 
Hey Classic-
I guess it depends on the light you're using.  A cfl or flouro tube doesn't put out much UVB, so it probably wouldn't hurt.  If you're using something with high output, I'd be afraid of doing harm to the plant.

From what I've read and been told, the UVB does 2 things- 1, it forces the plant to create more trichs to protect the calyxes from getting burned, and 2, it increases the conversion to THC from THCA and other cannabinoids.  So, if you've already got plenty of trichs, perhaps you'll be ok.

Let us know how it works for you.


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## classic_rocker_287 (Sep 8, 2009)

cool, my plants are working on there 4th week of flowering. At which point do they start developing trichs.


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## BBFan (Sep 9, 2009)

Hey Classic-
I think the trich development is strain specific, but my guess is the trichs should start showing within 10-15 days at around 40 days.  At least that's been my experience.  Good luck man.


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## Rolling Thunder (Sep 9, 2009)

01 - Marijuana Optics 

02 - Marijuana Optics Summary

03 - Marijuana Flowering at N35 Lat

04 - Marijuana and Artificial Light - A Frugal User's Guide

05 - A Light Set-Up for a Growing Chamber

06 - A Specialized Incandescent Light

07 - UVB Lamp Stand Set-Up

08 - More UVB Stuff

09 - UVB and Its Effects

10 - Finishing Buds Under Metal Halides

The You Tube video clip on uv-b was very much on the money, for the most part; though a little imprecise or unclear at certain places; as in the matter regarding whether or not indoor bud, grown without uvb supplementation, contains any realized THC. At one place he seemed to say that it did not, and that people were getting high off merely the THC precursors and cannabinoids themselves. Nor did he say much if anything about the ability of uva to activate THC, but it is clear that it must, or else indoor bud would be entirely impotent, since most horticultural HID's emit next to zero uvb. 

That uva does play a role in partially activating THC is recognized in the first article, above, entitled 'Marijuana Optics'. On the page showing how to construct an indoor growing chamber, the author recommends using a 1000w HP Mercury Vapour Lamp, on account of its ability to make fully realized the THC. I'm not sure if I'd ever use one as my principal light source, but I'd certainly not hesitate to recommend it as a good source of supplemental uvb lighting. 

In the ninth link, you will discover a 10.5 year old internet thread on the role of uvb in THC conversion. It contains a brief abstract of a controlled experiment conducted by ncga, regarding how much uvb supplementation to give your ladies. Ncga concludes that they should receive it throughout both the entire veg and flowering cycle, for maximum THC production. It is an interesting proposal, to say the least, and one well-worth some serious consideration. 

Concerning the last link, it is for a brief comment by Ed Rosenthal on finishing the flowering cycle under MH. That too merits due consideration, though I think it totally unnecessary if one supplements with proper uvb lighting, which is far more effective than anything a Metal Halide is capable of producing. Personally, I see no need of a metal halide other than for taking good pictures of your finished buds. If you want to make fully realized THC, use a proper uvb emitting lamp. But be careful. You know!

RT


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## BBFan (Sep 9, 2009)

Good info, RT.  Some interesting reading there, though I have read most of it already, particularly Joe Knuc's writings.
BTW- I couldn't get the 10th link to work.


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## Kupunakane (Sep 9, 2009)

Yo Ho my good friends,

   I carried a minor in Horticulture, and finished with a love of exotic plants. The introduction of UV may seem some what a mystery to most folks, but it has been in use for several decades.
 Remember that we are trying to copy the sun when we are growing indoors. The problems where most folks get hung up on,  is that most folks have never really studied LIGHT.

  We get a certain amount of the UV when we are outdoors, in fact that is what causes us to get a sunburn. Most of the UV spectrum is filtered by our own atmosphere, but enough makes it through to be a bit harmful if we are not careful with it, so we developed sunscreens etc. etc.

  Our using a small amount of UV is what causes the marijuana to produce a higher concentration of trichs as a balm to help protect the flowers and leaves from in a sense getting sunburned. It also wrecks havoc upon critters that want to take what you have, and in addition to that it does kill molds and bacterium. We do need to exercise caution for ourselves like turn it off before you get into it. 

  The biggest enemy we fight is the infra-red spectrum as it provides little of the spectrum that plants need for good and healthy growth. It's just heat, heat, heat. So one should be thinking along the lines of how do I get more of the proper spectrum that my babies need for real good healthy growth.

  We already know that grow tubes, T5's for instance are great and they do cut down on the heat footprint, as well as being less expensive to run. Now on top of that what could one use to further enhance the grow ?

  I have been running with a 90 watt tri-band LED in addition to the T5's. In every grow I have seen the difference that an LED can make . I'm not trying to push anyone in that direction, instead what I want to show you is that the proper spectrums will make a monster difference in your grows, but how do you attain that without spending a fortune on electrical bills , and how do you avoid the heat footprint that has busted so many good growers out there.??
  I applaud those of you who are willing to try to improve their grows, one might even go so far as to say that it is all a growing field of interest.
 Here is a grow schedual, that I use for my growbox, that measures 3'6'' X 4'6" X 6'6"


 veg cycle = six 48 inch T5 grow tubes
 90 watt Tri-band LED X 2 intro at 30 days
 UVB intro at 45 days 
 Lights run 24/7 with good airation and exchange
 Temps stay constant at 74-76* degrees

 Flowering cycle
six 48 inch T5's
The LEDS
the UVB bulb
and a 400 watt HPS
Lights flip to 12/12

I also run the lights at night to take advantage of the cooler temps, remembering that the ideal temp is around 74-78* degrees. It's also the heat sig that I am trying to escape, and it can be accomplished as I have done. Some might argue that the lighting is over-kill, and believe me you can bleach out your leaves easily by using too much light. Were this not the case and one could grow with autonomy you would see many a home burnt to the ground because of the multiple 1000 watters that would suddenly be in use. I am small scale, for just for me and mine, so I keep it small.
But then I think maybe someday ? HMmmm, maybe...

 Now the HPS does kick up the temps a bit, but I keep it controlled as the HPS is an enclosed light with venting in and out. I simply use inlines to help the air exchange, and a bath fan at the top of the box on the inside to help pull off any excess heat. Both the fans are vented to my charcoal canister for air filtration, and for the smell.

 This is how I drive, and it works so very nicely, but really it is from all the help over the years, as I was always an outdoor grower, who has now brought the sunshine indoors. In fact my growing my smoke indoors started here within MP. It has been you guys that have helped the most as I glean a little here and pick up a little there until I am where I am at.
 The real thanks goes to all the tireless growers that experiment and sometimes risk losing what they are working so hard for by trial and error. Take a look at this link, and don't be thrown off by the title. It is about the differing amounts of mercury in different types of lighting, but it is perhaps the best descriptor of lighting that I have ever run across. Just my $0.02 

hxxp://www.newmoa.org/prevention/mercury/imerc/factsheets/lighting.cfm


smoke in peace
KingKahuuna


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## BBFan (Sep 9, 2009)

Excellent post King.  And as usual, you're writing skills are amazing too.

Sounds like a great set-up.  I have a few questions.  What are your lumens per square in that flower schedule?  Do you switch the T-5's from cool to warm when you introduce the 12/12 schedule, or keep them blue?  How are you delivering the UVB?  What type of bulb?  I'm using a reptile flood that has a pretty good rating but does generate heat that I have to battle?

Thanks King.


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## Rolling Thunder (Sep 10, 2009)

BBFan said:
			
		

> Some interesting reading there, though I have read most of it already, particularly Joe Knuc's writings.


 
Joe Knuc is certainly an interesting guy, to say the least, though not uncontroversial. Marijuana Optics is essential reading, for all thoughtful growers, whether or not a person agrees or disagrees with this theory. I posted it here because I could immediately see his influence upon the dude`s thinking, in the video clip. It had Joe Knuc written all over it, though he never mentioned his name, as far as I can recall. 

I have yet run across a convincing rebuttal to his theory. Though short, Marijuana Optics is a relatively hard read, especially for the person who is reading it the first time. It is very compact and he has mastered the economy of words, making every one count for its full worth. It usually takes several reads, and some little cross-referencing, before his complete theory begins to make sense. 



			
				BBFan said:
			
		

> BTW- I couldn't get the 10th link to work.


 
Sorry about that. See the corrected link down below. I have taken this opportunity to preface it with and earlier statement by ED on the subject of supplemental UVB light. It is basic stuff but sets the record straight as to what ED believes and teaches. 

*Ed Rosenthal on Supplemental UVB Light:-*

There are three spectrums of UV light. UVA is the least harmful. This is the spectrum produced by black lights. UVC light is dangerous to all life. It is used in water purification systems to sterilize water. 

The light spectrum of interest to us is UVB. It affects life in many ways. In humans it causes tanning, skin aging, eye damage, and cancers. Other animals are affected by it in all sorts of ways. 

The earth's atmosphere filters UVB light. There is more UVB light at higher altitudes than at sea level. Also, sunlight at the equator takes the shortest route through the atmosphere. As the latitude increases, sunlight reaches Earth after going through more atmosphere because of its slanted path. 

Therefore UVB at the equator is much more intense than in temperate zones. That's one reason people tan or burn so fast in the tropics, and why skin cancer rates are higher in southern than northern states. 

A researcher conducted a controlled experiment in a greenhouse. He lit a group of high potency plants similarly except with the addition of UVB light to some groups. He found that the percentage of THC increased in a direct ratio with the increase in UVB light. This research confirms the addage that high altitude plants are more potent than those grown at low altitudes. 

If you look at old-world land races of cannabis, plants that have become adapted to the climate and altitude, the ratio of THC to CBD starts at 100:1 at the equator. At the 30th parallel (The Hindu Kush Valley) the plants have a ratio of 50:50. At the 45th parallel the ratio is near 1:100. This corresponds roughly with the amount of UVB light at these latitudes. There is much more UVB at the equator than the 45th parallel. 

Now, can you get more UVB light to your plants? Certainly it's true that Metal Halide lamps emit more UVB light than HPS lamps. Still, the amount that MH lamps emit is small. In fact, many manufacturers use UVB shielding glass to filter out most of the UVB that`s produced. The UVB light the plant receives from a MH lamp does increase the plant`s potency slightly at the cost of yield, but there are better ways to introduce UVB light into the grow room. They include reptile lights, which emit about ten percent uvb, and tanning lamps. 

The problem with using these lamps is that they are associated with increased number of cancers and many other problems. They should not be on when you are in the grow room. Not much research has been conducted on using them to produce higher THC values. I will do a full report in a future issue. 

(_ Cannabis Culture, _the Dec-Jan issue of _2002-2003, p. 85-86_ )

_Cannabis Culture Magazine - _Finishing Buds Under Metal Halides
By Ed Rosenthal - Friday, January 14 2005 

_Question. _Can I switch to metal halide during the last few weeks of bloom?

For years I've been growing under high pressure sodium (HPS) lights for both the grow and bloom phases, because HPS lamps emit more useable light per watt. This results in a better yield.

However, UV light stimulates resin production and metal halides (MH) emit more UVB light than HPS lamps. The bud has pretty much stopped growing by then so the reduced light output of the MH would not affect yields too much. Does it make sense to use MH lamps during the last few weeks of the bloom to stimulate more trichome/THC production?

Or is there a better way to add UV light to the end of the bloom phase?

Budleigh,
Charlottesville, Virginia

_Potency increases with more UVB light, so it would be a good idea to increase the amount of UVB they are receiving. _I like your idea of replacing the HPS lamps with MH during the last one to two weeks of flowering. Your reasoning, that flowering growth has slowed so that MH lamps, which emit considerably more light than HPS lamps, would increase the quality, could work. It's worth a try.

There are several ways you could make the switch over to MH lamps. You could replace the HPS bulbs with HPS-MH lamps. They work with standard HPS ballasts. Conversion ballasts can accommodate MH or HPS lamps at the flip of a switch.


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## Rolling Thunder (Sep 10, 2009)

Rolling Thunder said:
			
		

> Joe Knuc is certainly an interesting guy, to say the least, though not uncontroversial. Marijuana Optics is essential reading, for all thoughtful growers, whether or not a person agrees or disagrees with this theory.


 
Clarke's _Marijuana Botany_ is also essential reading. Chapter 4 contains his early observations on the effect of ultraviolet light upon the conversion of CBD to THC. It is a little dated, having been published nearly three decades ago; nevertheless, it gives us a tiny glimpse into what was known back then (pre-1980/81) concerning the role of uv light in the biosynthesis of THC. 

It is interesting to note that Clarke does not specifically refer to UVB, in MB, as the most important UV element or band in the THC conversion process. However, on page 10 of _Hemp Pests and Diseases_, he explicitly states that "under conditions of high UV-B exposure, Cannabis produces more THC." The 1987 article by Lydon is cited as the authority on that; entitled 'UV-B radiation effects on photoynthesis, growth and cannabinoid production of two _Cannabis sativa_ chemotypes;' which was published in _Photochemistry and Photobiology_ 46(2): 201-206. 

*Excerpt(s) from Cannabinoid Biosynthesis*

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 biosynthesis 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 psycho-activity 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 psychoactivity 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 bio-synthesis 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 homologs. 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. Ultraviolet 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. 

The ratio of THC to CBD has been used in chemotype determination by Small and others. The genetically determined inability of certain strains to convert CBD acid to THC acid makes them a member of a fiber chemotype, but if a strain has the genetically determined ability to convert CBD acid to THC acid then it is considered a drug strain. It is also interesting to note that Turner and Hadley (1973) discovered an African strain with a very high THC level and no CBD although there are fair amounts of CBC acid present in the strain. Turner* states that he has seen several strains totally devoid of CBD, but he has never seen a strain totally devoid of THC. 

Also, many early authors confused CBC with CBD in analyzed samples because of the proximity of their peaks on gas liquid chromatograph (GLC) results. If the biosynthetic pathway needs alteration to include an enzymatically controlled system involving the direct conversion of hydroxy-CBG acid to THC acid through allylic rearrangement of hydroxy-CBG acid and cyclization of the rearranged intermediate to THC acid, as Turner and Hadley (1973) suggest, then CBD acid would be bypassed in the cycle and its absence explained. 

Another possibility is that, since CBC acid is formed from the same symmetric intermediate that is allylically rearranged before forming CBD acid, CBC acid may be the accumulated intermediate, the reaction may be reversed, and through the symmetric intermediate and the usual allylic rearrangement CBD acid would be formed but directly converted to THC acid by a similar enzyme system to that which reversed the formation of CBC acid. If this happened fast enough no CBD acid would be detected. It is more likely, however, that CBDA in drug strains is converted directly to THCA as soon as it is formed and no CBD builds up. 

Also Turner, Hemphill, and Mahlberg (1978) found that CBC acid was contained in the tissues of Cannabis but not in the resin secreted by the glandular trichomes. In any event, these possible deviations from the accepted biosynthetic pathway provide food for thought when trying to decipher the mysteries of Cannabis strains and varieties of psychoactive effect. 

Returning to the more orthodox version of the cannabinoid biosynthesis, the role of ultraviolet light should be reemphasized. It seems apparent that ultraviolet light, normally supplied in abundance by sunlight, takes part in the conversion of CBD acid to THC acids. Therefore, the lack of ultraviolet light in indoor growing situations could account for the limited psychoactivity of Cannabis grown under artificial lights. 

Light energy has been collected and utilized by the plant in a long series of reactions resulting in the formation of THC acids. Farther along the pathway begins the formation of degradation products not metabolically produced by the living plant. These cannabinoid acids are formed through the progressive degradation of THC acids to CBN acid (cannabinolic acid) and other cannabinoid acids. The degradation is accomplished primarily by heat and light and is not enzymatically controlled by the plant. 

CBN is also suspected of synergistic modification of the psychoactivity of the primary cannabinoids, THCs. The cannabinoid balance between CBC, CBD, THC, and CBN is determined by genetics and maturation. THC production is an ongoing process as long as the glandular trichome remains active. Variations in the level of THC in the same trichome as it matures are the result of THC acid being broken down to CBN acid while CBD acid is being converted to THC acid. If the rate of THC biosynthesis exceeds the rate of THC breakdown, the THC level in the trichome rises; if the breakdown rate is faster than the rate of biosynthesis, the THC level drops. 

Clear or slightly amber transparent resin is a sign that the glandular trichome is still active. As soon as resin secretion begins to slow, the resins will usually polymerize and harden. During the late floral stages the resin tends to darken to a transparent amber color. If it begins to deteriorate, it first turns translucent and then opaque brown or white. Near-freezing temperatures during maturation will often result in opaque white resins. During active secretion, THC acids are constantly being formed from CBD acid and breaking down into CBN acid.[END OF EXCERPT]

MISCELLANEOUS OBSERVATION(S ON THE ABOVE):-

01. "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 ... ETC."

The above laboratory experiment is significant in that it proved that while UV-C plays an important role in THC biosynthesis, the light band of 235-285 nm is insufficient for creating fully realized THC. It must be in the 280-315 nm range. When Clarke says that "the yield of the conversion" rate, within that particular nm range, "is only about 15% THC acid," he means that the conversion was partial at best, and did not result in fully realized THC.


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## Rolling Thunder (Sep 12, 2009)

Rolling Thunder said:
			
		

> MISCELLANEOUS OBSERVATION(S ON THE ABOVE):-
> 
> 01. "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 ... ETC."
> 
> The above laboratory experiment is significant in that it proved that while UV-C plays an important role in THC biosynthesis, the light band of 235-285 nm is insufficient for creating fully realized THC. It must be in the 280-315 nm range. When Clarke says that "the yield of the conversion" rate, within that particular nm range, "is only about 15% THC acid," he means that the conversion was partial at best, and did not result in fully realized THC.


 
02. "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 biosynthesis of THC acids and minor cannabinoids."

Observe: When Clarke says "we," he is doubtless referring to the greater community of Cannabis botanists and biochemists, but also to himself. He is saying that the role of UV light in converting CBD to THC is the single thing that he personally knows the most about. And yet what follows upon this statement is a summary of all the things he was unsure of, back in 1980; all the possibilities that were then under serious consideration, regarding deviations from the genrally accepted biosynthetic pathway of conversion. 

03. "In any event, these possible deviations from the accepted biosynthetic pathway provide food for thought when trying to decipher the mysteries of Cannabis strains and varieties of psychoactive effect. 

"Returning to the more orthodox version of the cannabinoid biosynthesis, the role of ultraviolet light should be reemphasized. It seems apparent that ultraviolet light, normally supplied in abundance by sunlight, takes part in the conversion of CBD acid to THC acids. Therefore, the lack of ultraviolet light in indoor growing situations could account for the limited psychoactivity of Cannabis grown under artificial lights." 

Observe: "Returning to the more orthodox version of the cannabinoid biosynthesis, the role of ultraviolet light should be reemphasized." This is a very important statement, as it notes that within the field of cannabinoid research, there existed "a more orthodox version of the cannabinoid biosynthesis," that is to say, one that was widely held as "correct;" and which proved to be correct in 1987, with the publication of Lydon's definitive study. 

04. "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 psychoactivity 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." 

Observe: Here (above) is an example of the "unorthodox" thinking or speculation that was occurring 30 years ago, leading up to the publication of MB; and which the dude in the video clip appears to allude to, in his speculation(s) on how it was possible to get high off indoor buds, grown without UV-B supplementation. 

Since I'm not really in this field, nor have I ever taken a long-enough interest in it to engage in deeper research, I cannot tell where the science is currently at, in regard to either proving or disproving the above theory; especially in respect to the possible role of terpines "and other aromatic compounds" in biosynthetic process of fully realized THC or the potency of the bud. 

However, it is an interesting observation and one that plays into the question of gene linkages, which help to track and insolate the potency gene. Now, I know there are likely a few onlookers that balk at any mention or thought of a potency gene, but please understand: I am not an expert, and do not know if there is any concensus in the scientific community concerning the existence or absence of a "potency" gene. 

It seems to me, though, that at least one, if not a cluster of genes, must exist which determine potency, or else potency would not be a question of genetics, but rather enviromental forces alone. In that case, any strain of ditch weed could be cultivated into the most potent strain around. Personally, that's too much for my little brain to accept. No matter how hard I try, I cannot envision someone taking an impotent variety of ruderalis, and transforming it into the atomic bomb, without introducing a host of new genes into its genetic structure. 

Returning to the question of gene linkages, it is possible that the potency gene is linked to a distinct aroma, for example; and so one should observe closely those linkages in the parent plant and look for them in the off-spring, when tracking the potency gene during the selection process of breeding for enhanced potency. 

05. "It is also interesting to note that Turner and Hadley (1973) discovered an African strain with a very high THC level and no CBD although there are fair amounts of CBC acid present in the strain. Turner* states that he has seen several strains totally devoid of CBD, but he has never seen a strain totally devoid of THC." 

Rosenthal's Observation: "A researcher conducted a controlled experiment in a greenhouse. He lit a group of high potency plants similarly except with the addition of UVB light to some groups. He found that the percentage of THC increased in a direct ratio with the increase in UVB light. This research confirms the addage that high altitude plants are more potent than those grown at low altitudes. 

If you look at old-world land races of cannabis, plants that have become adapted to the climate and altitude, the ratio of THC to CBD starts at 100:1 at the equator. At the 30th parallel (The Hindu Kush Valley) the plants have a ratio of 50:50. At the 45th parallel the ratio is near 1:100. This corresponds roughly with the amount of UVB light at these latitudes. There is much more UVB at the equator than the 45th parallel." 

06. "Light energy has been collected and utilized by the plant in a long series of reactions resulting in the formation of THC acids. Farther along the pathway begins the formation of degradation products not metabolically produced by the living plant. These cannabinoid acids are formed through the progressive degradation of THC acids to CBN acid (cannabinolic acid) and other cannabinoid acids. The degradation is accomplished primarily by heat and light and is not enzymatically controlled by the plant." 

Observe: I read somehwere recently that they discovered some cured buds, during an archeological dig of an old burial sight. It was said to be thousands of years old and tested potent. Its potency had not been entirely lost, which confirms the above statement by Clarke that "degradation is accomplished primarily by heat and light and is not enzymatically controlled by the plant." For those that have'nt figured it out yet, don't leave your stash box in the car glove compartment, during the hot summer days, for heaven's sake! And for long term storage, pack up those buds really good, and put them in the fridge or even freeze them!



			
				Rolling Thunder said:
			
		

> _Cannabis Culture Magazine - _Finishing Buds Under Metal Halides
> By Ed Rosenthal - Friday, January 14 2005
> 
> _Potency increases with more UVB light, so it would be a good idea to increase the amount of UVB they are receiving. _I like your idea of replacing the HPS lamps with MH during the last one to two weeks of flowering. Your reasoning, that flowering growth has slowed so that MH lamps, which emit considerably more light than HPS lamps, would increase the quality, could work. It's worth a try.


 
When Rosenthal says " ... that MH lamps, which emit considerably more light than HPS lamps," it is obvious, from the immediate context, that he means UV light. 

RT


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## BBFan (Sep 12, 2009)

Great post RT.
Thanks.


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## Rolling Thunder (Sep 16, 2009)

BBFan said:
			
		

> From what I've read and been told, the UVB does 2 things- 1, it forces the plant to create more trichs to protect the calyxes from getting burned, and 2, it increases the conversion to THC from THCA and other cannabinoids.


 


			
				Rolling Thunder said:
			
		

> In the ninth link, you will discover a 10.5 year old internet thread on the role of uvb in THC conversion. It contains a brief abstract of a controlled experiment conducted by ncga, regarding how much uvb supplementation to give your ladies. Ncga concludes that they should receive it throughout both the entire veg and flowering cycle, for maximum THC production. It is an interesting proposal, to say the least, and one well-worth some serious consideration.


 
The 'UV-B and It's Effects' link, designated above as link no. nine, is not so much a thread, strictly speaking, as it is a collection of posts originally made on the old Bcga website, over ten years ago now. It can be ascertained from several of the comments that Vic High, Soul, OT1 and ncga, had all been working with UV-B supplementation for several years, probably beginning in the early to mid 90's. I suspect that the 1987 Lydon study may have had something to do with that, which is referenced by both Clarke and Knuc: 

"Pate (1983) indicated that in areas of high ultraviolet radiation exposure," (as Knuc duly notes,) "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)."

Now, the 'ncga' controlled experiment made a very interesting discovery, relating to and developing upon your first point, BBFan, quoted above: "UVB ... forces the plant to create more trichs to protect the calyxes." For those who haven't looked at it (the ncga abstract) yet, it was a 3 year controlled experiment, consisting of 7 different controlled grows, begun in '93 and completed in '96, or thereabouts. This is the sum of what he (or they) discovered: 

'Ncga's Brief Observations:- 

"The bulb should be replaced every year. There seamed to be some drop off in the results after the first year but the results were still better than without UVB. 

"I noticed that some plants had a hard time acclimating to the UVB. At first these low tolerance plant exhibited a lot of leaf curl or sunburn when introduced to the UVB. However the younger leaves quickly adapt to the UVB light. 

"It is important to introduce the plants at a young (short) age so a most of the plant is exposed over a long period of time. The results are not as prominent over the entire plant and is less noticeable. 

"In other words, a plant started with most of it exposed over its life to the UVB. The lower shoots if exposed when young will have more resin on them than those that were not exposed at a young age."[End of Ncga's Observations]

Not sure what 'ncga' stands for but I have often imagined it meant something like "North Carolina Grower's Association;" and that the grower known as 'ncga' was likely a member of that co-op, or maybe even one of its founders. If anyone knows for sure, please let us all know! 

At any rate, whatever criticism might be made of the experiment, I think it has some merit and should be taken into consideration by all; and most especially by those who are yet unconvinced of the benefits of UV-B, to cultivating a more potent indoor bud. 

Ncga directly observed, first-hand, over a period of 3 years, that "the lower shoots, if exposed when young, will have more resin on them than those that were not exposed at a young age." Now, this is a very interesting and useful observation, I think, as it is a strong argument for supplementing the plants with UV-B during the veg period as well; and not just when the trichomes begin to visibly form. 

As Clarke states, light energy "is collected and utilized by the plant in a long series of reactions resulting in the formation of THC acids (MB, p. 135) It is reasonable to believe these chemical reactions to UV-B begin even during the veg period, when the plant is sizing up its enviroment, and pre-programing its defense mechanism for trich production. There is no question in my mind that the plant begins to react against UV-B from the very moment of its first exposure to it!!

It is very likely the chemical reaction to the UV-B is stored away, and that the more of it the plant has accumulated before the onset of its bloom, the more trichome it will produce. Continued reflection upon this leads me to believe it is somewhat irrational or unreasonable to think UV-B exposure during the veg period does *not* set or pre-program the plant for far greater trich production. 

When ncga says that: "The results are not as prominent over the entire plant and is less noticeable," I take him to mean there that the enhanced trich formation, as a direct result of supplemental UV-B, is not as prominent or noticeable when it is introduced later, or even at the onset of trich formation. The earlier it is introduced, as ncga observes, the greater the difference it makes, over the entire plant and not just the top of its main cola. 

At any rate, I thought the information under the `UV-B and It`s Effects` link would be of some interest to you all, for a variety of reasons, not least of which are the statements it contains by a few of the more advanced growers on the scene today, such as OT1, Soul, and Vic High, not to mention ncga. They were all insightful remarks, to be sure, but I was struck more by OT1`s observations and the findings of ncga`s controlled experiment. 

OT1 is very keen to point out that potent equatorial drug cultivars are adversely affected by the stark absence of adequate UV-B light, indoors. He argues that the removal of the UV-B photon from the indoor light stream will cause a potent drug cultivar to mutate, or drift away from its genetic programing within a short span of four or five consecutive indoor generations. 

In this connection, Joe Knuc observes that it is the pure equatorial sativas that stand to gain the most *from* supplemental UV-B, indoors! It is observed at one point that the Dutch seed companies realized their prized strains were experiencing a noticeable decline or drop-off in potency, which they could not attribute to any other limiting factor, except the missing UV-B photon. Once they discovered this, they introduced UV-B supplementation to their indoor crops. 

So let us observe, then, that UV-B supplementation was already widely practiced in the Dam over ten years ago; and I suspect even more widely today, a full decade later! And it is very likely this experimentation has been going on even much longer than that, as King intimated; from at least 1987, with the publication of Lydon's definitive study. Btw, KK, please pardon my unfortunate oversight in failing to thank you earlier for your very interesting post. I share BBFan`s sentiment(s), in regard to your elaborating further on the details of your program/system:- 



			
				BBFan said:
			
		

> Sounds like a great set-up. I have a few questions. What are your lumens per square in that flower schedule? Do you switch the T-5's from cool to warm when you introduce the 12/12 schedule, or keep them blue? How are you delivering the UVB? What type of bulb? I'm using a reptile flood that has a pretty good rating but does generate heat that I have to battle?


 
I, too, am keen to learn the answers to the above questions; and others, concerning the LED`s. After all, it isn`t everyday we get to hear from someone with university level horticultural training!  It was very interesting to read, for example, your observation about the decades old horticultural practice of supplementing indoor crops with UV-B lighting. 

With regard to the LED`s, though, you appear to rate them very highly, mainly on account of their superior light spectrum; so I am naturally curious as to why you have`nt traded in the HPS yet for a 300w LED? Are you moving at all in the direction, or do you plan to carry on with the status quo, in terms of your current light set-up? I'd also like to know why you have decided not to supplement the CO2 levels, seeing the extent to which you have gone with the lighting? 

RT


(Edited one word, changing "of" to "from," in rthe fourth paragraph from the bottom.)


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## BBFan (Sep 17, 2009)

Again, another excellent post RT and thank you for helping disseminate the information for us.

I have not yet seen a response from King, but would be interested to see his follow up comments.


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## Rolling Thunder (Sep 19, 2009)

Thanks, BBFan. I'm just glad to be of some minor assistance!  Incidentally, when surfing the web earlier today, I came across a very interesting thread (somewhere else) on this subject, which will likely be of great interest to yourself as well. It's entitled: 'UV-B Lights?' @ hXXp://forum.grasscity.com/general-indoor-growing/336317-uvb-lights.html


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## BBFan (Sep 19, 2009)

Thanks RT- I'll definitely check it out.


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## leafminer (Sep 20, 2009)

Well, if you want to try the effects and don't mind the risk of UV burns or death through electric shock, remove the outer bulb from an HPS discharge lamp. But don't blame me if your plants curl up and die.


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## Rolling Thunder (Sep 20, 2009)

leafminer said:
			
		

> Well, if you want to try the effects and don't mind the risk of UV burns or death through electric shock, remove the outer bulb from an HPS discharge lamp. But don't blame me if your plants curl up and die.


 
:holysheep:


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## BBFan (Sep 20, 2009)

leafminer said:
			
		

> Well, if you want to try the effects and don't mind the risk of UV burns or death through electric shock, remove the outer bulb from an HPS discharge lamp. But don't blame me if your plants curl up and die.


 

Thank you very much for your concern and your constructive post! :aok:


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