# UV light or photoinhibition



## 2Hearts (Feb 3, 2016)

In my study of botany (especially marijuhana) i have come across some interesting stuff but one thing has stuck out recently and that is the minor debate that UV light has the same effects as too much normal light/Photoinhibition.

It is theorized by some that the plants response to UV light is exactly the same as when too much normal light is provided and hence the same results can be achieved.

I have noted that no member has proved the benefits of UV light and certainly there are no conclusive studies that i have read that link extra THC production to the quantity of UV light provided except that it can cause damage to the plant cells and this is the same system that is seen when providing too much (NON) UV light.

Certainly the idea that you can promote more THC with just ordinary light has caused quite the discussion in non Marijuwana circles and it certainly does seem that what some try to achieve with all those UV bulbs could easily be demonstrated by increasing lumens to a detrimental level.

The plant should react to the damage, whether that be UV or just too much lumens, and produce the same stress response.

Certainly interesting to read and something i have seen before i.e. very sticky buds from over exaggerated lumens without having to add UV bulbs.


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## cannawizard (Feb 4, 2016)

2Hearts said:


> In my study of botany (especially marijuhana) i have come across some interesting stuff but one thing has stuck out recently and that is the minor debate that UV light has the same effects as too much normal light/Photoinhibition.


Have you personally experimented with the UV spectrum (UVa/UVb/UVc) in-regards to cannabis? 
(and if yes), what anecdotal data were you able to ascertain? 

https://www.reddit.com/r/Head2HeadMG/comments/2p1j5r/an_introductory_primer_on_the_utility_of_uv_light/
(good read)

http://silassativarius.org/2014/10/03/does-exposing-your-plants-to-uvb-increase-thc-production/
(info on UVR8 gene, skip the LED plug in the end)


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## Kingrow1 (Feb 4, 2016)

cannawizard said:


> Have you personally experimented with the UV spectrum (UVa/UVb/UVc) in-regards to cannabis?
> (and if yes), what anecdotal data were you able to ascertain?
> 
> https://www.reddit.com/r/Head2HeadMG/comments/2p1j5r/an_introductory_primer_on_the_utility_of_uv_light/
> ...


I never bothered experimenting with UV because i could never find a thread where any difference has been noted between that and a control grow so seemed pointless. If there was any kind of credible evidence that increased thc or production im sure companies and members would have jumped ot it like flies to shit as you see with some other products that have sprung up in the last 10 years.

There is two ideas about UV and Photoinhibition, one is they do the same thing and the other is that they are seperate systems......

I wrote this thread because the results people try to produce with UV seem easy to produce with Photoinhibition and where as UV seems to be failing to produce correlated results photoinhibition seems to be producing what UV should with a lot more ease (and obviously electricity costs).

Just saying that UV and Photoinhibition seem to produce the same end results and the stickiest thc buds ive had were from over lighting my flower room.


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## rkymtnman (Feb 4, 2016)

i use uvb cfls. alot cheaper to run 2 of these vs overlighting with a HID in my opinion.


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## cannawizard (Feb 5, 2016)

Kingrow1 said:


> I never bothered experimenting with UV because i could never find a thread where any difference has been noted between that and a control grow so seemed pointless. If there was any kind of credible evidence that increased thc or production im sure companies and members would have jumped ot it like flies to shit as you see with some other products that have sprung up in the last 10 years.
> 
> There is two ideas about UV and Photoinhibition, one is they do the same thing and the other is that they are seperate systems......
> 
> ...


Thanks for the input, got stuck reading a couple of links concerning "photoinhibition" 

Did you run into any problems increasing "light intensity" on your cannabis plants?
(ex: http://www.growweedeasy.com/too-much-light)

~ all i can add to the whole UV thing is _genetics_.. not all strains/phenos respond the same


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## Mount (Feb 5, 2016)

Been thinking about adding UV to my next grow, anyone read these?

http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.1987.tb04757.x/full

http://www.hightimes.com/read/grow-hack-how-use-uv-lamp-increase-thc

https://silassativariusdotorg2.files.wordpress.com/2016/01/uvb-effects-on-photosynthesis-growth-and-cannabinoid-produciton-in-cannabis-sativa.pdf


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## Kingrow1 (Feb 5, 2016)

Ive read a lot about UV but ive never seen anything conclusive to make me want to try. Uv light isnt very plant friendly which is where the link to photoinhibition/too much light comes from as both should force the plant to protect itself.

I cant remember which member did it but not so long ago someone here tried to do a comprehensive grow with UV included. Many have tried but none seem to confirm it made better plants.

Naturally the sun kicks out a fair amount of UV on a sunny day so there must be a lot of truth to it but as for better plants, ive not seen anything that has convinced me yet.

I would add UV to my grow if i could yeild more.


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## rkymtnman (Feb 6, 2016)

Kingrow1 said:


> I would add UV to my grow if i could yeild more.


it won't increase yield at all. 
i have seen some info where alot of strains from high uvb areas (high altitude, equator, etc) have higher thc.

supposed to increase trichomes which in effect act as sunscreen for the plant to block uvb.

grow lights provide hardly any uvb. especially hps. and especially if the bulb is blocked by glass of a cooled hood. 

for $30 for 2 23w cfls and 2 light sockets, it's well worth it. why not try to recreate the sun as much as possible?


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## Kingrow1 (Feb 6, 2016)

rkymtnman said:


> it won't increase yield at all.
> i have seen some info where alot of strains from high uvb areas (high altitude, equator, etc) have higher thc.
> 
> supposed to increase trichomes which in effect act as sunscreen for the plant to block uvb.
> ...


By yeild i mean more thc (sorry) but obviously no reduction in bud size. Those trichs should also be increased by too strong of a light (so the link goes).

Over in my area we have a vast selection of various different UV bulbs that are in T8 and T5 flourescent size so if i did id use them rather than the cfls.

Coincidentally flourescents use a shed load of UV rays but they are absorbed by the phosphorus coating inside the bulb, a UV flourescent just allows the UV through the bulb without being absorbed (by my thinking) although id need to check that out.

They push cfls hard and ive used every single size but always found that although they are a little weak when compared to the equivelant wattage in other bulbs i.e. a 24 watt cfl is a small not that powerfull light on its own but a 24watt T5 is much brighter. The 250watt cfl i had was not as bright as a 250watt hps.

Cfls and leds just cant quite compare but with the ever advancing technology im sure they will sooon become a lot better.


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## rkymtnman (Feb 6, 2016)

Kingrow1 said:


> Over in my area we have a vast selection of various different UV bulbs that are in T8 and T5 flourescent size so if i did id use them rather than the cfls.


agreed. the best option inmy opinion would be to try to add some uv bulbs from a tanning bed. 

i think the effective range of my cfls are 20 inches. 

most reptile websites have all types of uvb bulbs in stock. i have one more grow on these cfls and i'm gonna switch to a t5 or t8 setup. would be easier and have better coverage in my flower room.


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## rkymtnman (Feb 6, 2016)

my main question about using too much HID vs UVB bulbs is how do you know what light level with a HID is too much?

let's say i have a 600 hps in my 3x4 room. is adding an extra 250 hps gonna do it? would i need a 400? would i need another 600? seems like it would be hard to figure out the threshold for the HID


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## Kingrow1 (Feb 6, 2016)

rkymtnman said:


> my main question about using too much HID vs UVB bulbs is how do you know what light level with a HID is too much?
> 
> let's say i have a 600 hps in my 3x4 room. is adding an extra 250 hps gonna do it? would i need a 400? would i need another 600? seems like it would be hard to figure out the threshold for the HID


Assuming were still talking photoinhibition you can find the threshold by finding the point a plant stops stretching for the light. At this point we can assume the plant is no longer looking for extra light. Hard to judge for flowering but as a plant grows you can get a general idea of when its happy and when it wants more. The rest is just experience and tweaking things grow after grow i guess. Obviously as a plant grows it will require more and more to a point.


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## BobCajun (Feb 15, 2016)

I'm sticking with UV-A myself for now. It's known that plants do use UV-A, it increases phenolics, which are building blocks for THC. CFL blacklights are cheap and almost all of the spectrum is UVA. So far with 52w/sq m I've noticed leaves curl downward toward the tips and some browning of leaf margins. I tried some and it did seem more potent than last time without UV. They're growing well enough. It's just the final 2 weeks I'm using it, 12 hrs a day.


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## Greenthumbs21 (Feb 27, 2016)

You want to go to uvb nanometers.

http://www.internationalhempassociation.org/jiha/iha01201.html

I can go on for days about ultraviolets and many see a change in the next run after adding uvb
It doesn't only increase protection it also changes the chemical make up and stacks the cuticle of the trich thicker.


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## Greenthumbs21 (Feb 27, 2016)

@ArcticOrange whats your take on the subject?


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## Greenthumbs21 (Feb 27, 2016)

rkymtnman said:


> my main question about using too much HID vs UVB bulbs is how do you know what light level with a HID is too much?
> 
> let's say i have a 600 hps in my 3x4 room. is adding an extra 250 hps gonna do it? would i need a 400? would i need another 600? seems like it would be hard to figure out the threshold for the HID


Its not so much about pumping more watts... its more about hitting your plant with the right nanometers. Photon color is much more important.


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## Greenthumbs21 (Feb 27, 2016)

rkymtnman said:


> it won't increase yield at all.
> i have seen some info where alot of strains from high uvb areas (high altitude, equator, etc) have higher thc.
> 
> supposed to increase trichomes which in effect act as sunscreen for the plant to block uvb.
> ...


The increase in yield comes from the extra trich coverage.


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## ArcticOrange (Feb 28, 2016)

Can confirm, was running uva without uvb and have since added the uvb, definitely made a difference, ill take some pictures tomorrow, ive always got some going in my thread as well


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## qwizoking (Feb 28, 2016)

2Hearts said:


> The plant should react to the damage, whether that be UV or just too much lumens, and produce the same stress response.


No...its not really a stress response, as mentioned uvr8 is activated which increases precursors to olivetolic acid

Raising light intensity, can bleach from too little chlorophyll production. Leaves will widen and thicken, buds are tight etc..
These are hormonal responses but trich heads are not directly affected.. so long as yiu don't fry them. This is very different from the response seen from uvb and activated receptors


Theres no point where the plant just stops stretching. I can grow 3-5 fingered plants all the way to harvest that are just as frosty potent and tasty as the same strain blasted with light pushing 11-13. fingers.
Thats not how it works lol



Yea i already told you my thoughts in your uva thread... good luck man, doesnt seem like a good idea


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## BobCajun (Feb 28, 2016)

ArcticOrange said:


> Can confirm, was running uva without uvb and have since added the uvb, definitely made a difference, ill take some pictures tomorrow, ive always got some going in my thread as well


But did the UV-A alone increase potency at all? Maybe both together would be good. I actually had a couple blacklight CFLs, which put out all UV-A, and I put them in splitter sockets with the Reptile lights. The CFLs put out a huge spike in the UV-A range, way more than the reptile lights. But I still have some UV-B from the rep lights plus some extra PAR light, since it's just a tropical rep light rather than desert (I bought the wrong one, oh well).


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## ArcticOrange (Feb 28, 2016)

Heres a scientific study so everyone can stop saying theres no evidence or its all anecdotal.


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## ArcticOrange (Feb 28, 2016)

I dont think too much light has the same effect, id stick with 5-10% uv light and grow as normal my .02.


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## BobCajun (Feb 28, 2016)

ArcticOrange said:


> I dont think too much light has the same effect, id stick with 5-10% uv light and grow as normal my .02.


I'd like to see an experiment to see how close reptile CFLs need to be to make a significant difference.


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## ArcticOrange (Feb 28, 2016)

I keep mine 6 inches away, ive noticed the difference, you can feel them on your skin, itll sunburn you lol


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## ArcticOrange (Feb 28, 2016)




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## BobCajun (Feb 28, 2016)

ArcticOrange said:


> View attachment 3619430


I put a couple 13w uvb 5s in a cab grow but I mounted them up at the top so probably 18" away. I guess they really need to be about 8" away at most. 

What if reptile lights were cheap and you just put about 20 26w UVB-5 bulbs in a 3'x3' area as the actual grow lights? I bet you'd get some potent stuff then. As prices are now though, it would cost you about $600.


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## ArcticOrange (Feb 28, 2016)

I dont think they have enough PAR light spectrum to be used alone.i shoot for the higher end of avg on earth. Mimic high altitudes where the most potent natural strains have been found.


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## Greenthumbs21 (Feb 28, 2016)

BobCajun said:


> I'd like to see an experiment to see how close reptile CFLs need to be to make a significant difference.


Well to give you an idea.. i have let them touch a leaf over night and they didnt burn it.. and the box said its not effective for lizzards after like 13 inches so.... anywhere in between is good


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## ~CReePeR~ (Feb 29, 2016)

How should UVB be run during a grow, 1) from start to harvest 2) from start of flower cycle to harvest or 3) 2-4 weeks into flower cycle (depending on length of cycle) to harvest?


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## BobCajun (Feb 29, 2016)

~CReePeR~ said:


> How should UVB be run during a grow, 1) from start to harvest 2) from start of flower cycle to harvest or 3) 2-4 weeks into flower cycle (depending on length of cycle) to harvest?


This Dutchman guy did some experiments with UV and said you only need it the last 2 weeks. In fact he said he got down as low as 1 week and it still worked but he recommends 2. I guess he uses long fluorescents.


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## ~CReePeR~ (Feb 29, 2016)

Thank BobCajun, I figured it was a short time.


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## Greenthumbs21 (Feb 29, 2016)

~CReePeR~ said:


> How should UVB be run during a grow, 1) from start to harvest 2) from start of flower cycle to harvest or 3) 2-4 weeks into flower cycle (depending on length of cycle) to harvest?


Well in order to mimic an outdoor flower cycle its used throughout... i add them right after stretch is done about week 2 till chop. The last 2 weeks is good for maturing trichs already there but they help in the early stages building protection too.


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## ~CReePeR~ (Feb 29, 2016)

Wow, looks like a worth wile experiment to try


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## qwizoking (Mar 1, 2016)

It should be used throughout


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## rkymtnman (Mar 1, 2016)

BobCajun said:


> I'd like to see an experiment to see how close reptile CFLs need to be to make a significant difference.


i have 23 watters 15.0 and their effective range is up to 20 inches


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## rkymtnman (Mar 1, 2016)

Greenthumbs21 said:


> Well in order to mimic an outdoor flower cycle its used throughout... i add them right after stretch is done about week 2 till chop. The last 2 weeks is good for maturing trichs already there but they help in the early stages building protection too.View attachment 3620245


i do the same. after stretch until chop


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## BobCajun (Mar 1, 2016)

I haven't found much if any difference with the rep bulbs, though they are about 18" away so maybe they need to be quite close. The problem there is that they would block some of the main light. Now I'm trying using the UV-B for a week and then stopping using them for the last week. Maybe they will then put out more resin to get ready in case they get dosed again.


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## rkymtnman (Mar 1, 2016)

BobCajun said:


> I haven't found much if any difference with the rep bulbs, though they are about 18" away so maybe they need to be quite close. The problem there is that they would block some of the main light. Now I'm trying using the UV-B for a week and then stopping using them for the last week. Maybe they will then put out more resin to get ready in case they get dosed again.


i used to run the uv for basically the whole 12 hrs. i'm trying on this grow to do it just from 10 am to 2pm to mimic the higher uv during the sunniest part of the day. we'll see how it works.


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## BobCajun (Mar 1, 2016)

rkymtnman said:


> i used to run the uv for basically the whole 12 hrs. i'm trying on this grow to do it just from 10 am to 2pm to mimic the higher uv during the sunniest part of the day. we'll see how it works.


I read an article where they only used UV for an hour at lights on and an hour before lights off and it worked. Could probably use them for an hour before dark only.


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## Greenthumbs21 (Mar 1, 2016)

BobCajun said:


> I haven't found much if any difference with the rep bulbs, though they are about 18" away so maybe they need to be quite close. The problem there is that they would block some of the main light. Now I'm trying using the UV-B for a week and then stopping using them for the last week. Maybe they will then put out more resin to get ready in case they get dosed again.


Thats your problem. ... keep them within a foot... i keep them at 6 inches and move them around


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## Greenthumbs21 (Mar 1, 2016)

rkymtnman said:


> i have 23 watters 15.0 and their effective range is up to 20 inches


What is the name brand on your 15.0 bulbs?... please share a link... im always looking for cheaper bulbs but amazon is usually the place to go to


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## The Nine (Mar 2, 2016)

Would these be any good for intermittent use for the the last 2 weeks of flower?
http://www.natureshydroponics.com/big-blue-ozone-generators/uv-ozone-generators


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## BobCajun (Mar 2, 2016)

The Nine said:


> Would these be any good for intermittent use for the the last 2 weeks of flower?
> http://www.natureshydroponics.com/big-blue-ozone-generators/uv-ozone-generators


That's UV-C, deadly to all life. If you click on the replacement tube it tells you about it.


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## BobCajun (Mar 2, 2016)

Greenthumbs21 said:


> Thats your problem. ... keep them within a foot... i keep them at 6 inches and move them around


I guess I'll have to work on getting them that close then. They are just little 13w bulbs after all. You couldn't even grow a plant with a warm white of that wattage with it being more than a few inches away, so it makes sense that it's the same for UV bulbs.


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## Greenthumbs21 (Mar 2, 2016)

The Nine said:


> Would these be any good for intermittent use for the the last 2 weeks of flower?
> http://www.natureshydroponics.com/big-blue-ozone-generators/uv-ozone-generators


It goes uva..uvb..uvc..xray..gamma ray. UvB is as low as you want to go for skin and plants.


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## Greenthumbs21 (Mar 2, 2016)

BobCajun said:


> I guess I'll have to work on getting them that close then. They are just little 13w bulbs after all. You couldn't even grow a plant with a warm white of that wattage with it being more than a few inches away, so it makes sense that it's the same for UV bulbs.


The 26 watter work much better but ya same principle... CLOSE


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## BobCajun (Mar 2, 2016)

Greenthumbs21 said:


> The 26 watter work much better but ya same principle... CLOSE


Unfortunately, I totally screwed up on my first rep bulb buy. I got too low a wattage and I got tropical instead of desert. Couldn't have gone worse really.


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## BobCajun (Mar 2, 2016)

Greenthumbs21 said:


> View attachment 3621908
> It goes uva..uvb..uvc..xray..gamma ray. UvB is as low as you want to go for skin and plants.


Apparently it's the 290nm band that's used by cannabis.


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## The Nine (Mar 3, 2016)

BobCajun said:


> That's UV-C, deadly to all life. If you click on the replacement tube it tells you about it.


That's why I said intermittently. Would this not kick the plants defence mechanism ( thc production) into high gear for the last 2 weeks say on for a few mins every hour as the plant tries to stay alive for pollination?
I'm just asking questions here mate, not claiming any thing, we are all searching for better methods/techniques.


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## The Nine (Mar 3, 2016)

Greenthumbs21 said:


> View attachment 3621908
> It goes uva..uvb..uvc..xray..gamma ray. UvB is as low as you want to go for skin and plants.


I certainly wouldn't be in the room/tent whilst they were running and I think using good quality extract to quickly remove the o3 that these generators produce will limit the harm. 
I will wait and see if anyone else has tried this, this forum is a wealth of information of peoples experimentations with the sacred plant.


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## rkymtnman (Mar 3, 2016)

Greenthumbs21 said:


> What is the name brand on your 15.0 bulbs?... please share a link... im always looking for cheaper bulbs but amazon is usually the place to go to


it's the exo terra brand. off amazon as well. i actually ordered 10.0 and they sent 15.0.


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## BobCajun (Mar 3, 2016)

The Nine said:


> That's why I said intermittently. Would this not kick the plants defence mechanism ( thc production) into high gear for the last 2 weeks say on for a few mins every hour as the plant tries to stay alive for pollination?
> I'm just asking questions here mate, not claiming any thing, we are all searching for better methods/techniques.


The UV light band used by cannabis to produce more phenolic compounds (which lead to THC) is 290 nm. Anything below that would be useless and incredibly dangerous and harmful. No living thing can take UVC, fortunately the ozone layer filters it all out of sunlight.


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## Rayne (Mar 3, 2016)

~CReePeR~ said:


> How should UVB be run during a grow, 1) from start to harvest 2) from start of flower cycle to harvest or 3) 2-4 weeks into flower cycle (depending on length of cycle) to harvest?


If you haven't added UV A/B supplementation in a previous grow just added one or two lights (T-5 or cfl) to your current grow at whatever stage your are at. Don't wait for "Peer" review to try something. 

For the individual who are savvy enough, the fact that UV A/B is produced by the sun aught to be enough reason to use UV A/B in an indoor grow season.

My current grow, has had UV A/B supplementation since the beginning stages.

For those who grow for "Hash" production...yield increases. For those who grow for flower production...yield stay about the same.


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## BobCajun (Mar 3, 2016)

Rayne said:


> If you haven't added UV A/B supplementation in a previous grow just added one or two lights (T-5 or cfl) to your current grow at whatever stage your are at. Don't wait for "Peer" review to try something.
> 
> For the individual who are savvy enough, the fact that UV A/B is produced by the sun aught to be enough reason to use UV A/B in an indoor grow season.
> 
> ...


But you must also consider the fact that UV reduces growth. It's sort of a tradeoff, you can either have maximum growth and weight yield but with lower secondary plant products like THC, or the other way around. Maybe cannabis can take UV more than the other plants in the studies, IDK, but it's probably pretty similar.


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## Rayne (Mar 4, 2016)

BobCajun said:


> But you must also consider the fact that UV reduces growth. It's sort of a tradeoff, you can either have maximum growth and weight yield but with lower secondary plant products like THC, or the other way around. Maybe cannabis can take UV more than the other plants in the studies, IDK, but it's probably pretty similar.


If you want the plant to develop to it's fullest genetic potiential. UV A/B light and Infrared light must be included. 

Outdoor Sativa strains get bathed in UV A/B plus infrared red and still grow at least 10 foot tall.


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## The Nine (Mar 4, 2016)

BobCajun said:


> The UV light band used by cannabis to produce more phenolic compounds (which lead to THC) is 290 nm. Anything below that would be useless and incredibly dangerous and harmful. No living thing can take UVC, fortunately the ozone layer filters it all out of sunlight.


Thanks

I found this on another forum


> _Excellent response and a lot of good information. You definitely make the point that UV-C is not to be used without a complete understanding of the handling and dosing of this spectrum. I generally agree with everything put forth but would like to point out some mischaracterizations regarding the way power and energy have been discussed for the purposes of using UV-C for plant sterilization._
> 
> Powdery mildew requires around 1800 u watts of uvc to kill the spore. On an 11 watt uvc bulb that means a quick once over with the lamp will kill all spores the light falls on.
> 
> ...


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## BobCajun (Mar 4, 2016)

The Nine said:


> Thanks
> 
> I found this on another forum


It might be okay in an automated light moving system, but I wouldn't use the handheld ones. The amount of microwatts put out is huge at close distance. Your entire body would have to be covered and you'd need special goggles. Just not worth it to kill powdery mildew. UVB is dangerous enough, don't even think about UVC unless it's in a completely enclosed area like a sterilizing cabinet.


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## The Nine (Mar 4, 2016)

BobCajun said:


> It might be okay in an automated light moving system, but I wouldn't use the handheld ones. The amount of microwatts put out is huge at close distance. Your entire body would have to be covered and you'd need special goggles. Just not worth it to kill powdery mildew. UVB is dangerous enough, don't even think about UVC unless it's in a completely enclosed area like a sterilizing cabinet.


Thanks again mate 
I hear you, and you are makng sense.


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## Greenthumbs21 (Mar 5, 2016)

This is how to use uvb... then uvc


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## DankaDank (Mar 9, 2016)

Im a bit conflicted regarding this topic, this reddit thread seems to make sense https://www.reddit.com/r/Head2HeadMG/comments/2nt3ml/red_white_blue_full_spectrum_an_led_color_choice/ 
but then there's this
http://medicalmarijuanagrowing.blogspot.co.uk/ wich is apparently an actual test (just read from the third page and scip the mildew shit).
The dankest strains do come from high altitude areas so could it be more uv or simply more light or even different atmospheric conditions and lower altitude areas seem to have more cbd rich strains, so maybe uva and b are detrimental to cbd ,so many questions and so little tests better get my shit together and start some test journals


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## Greenthumbs21 (Mar 21, 2016)

DankaDank said:


> Im a bit conflicted regarding this topic, this reddit thread seems to make sense https://www.reddit.com/r/Head2HeadMG/comments/2nt3ml/red_white_blue_full_spectrum_an_led_color_choice/
> but then there's this
> http://medicalmarijuanagrowing.blogspot.co.uk/ wich is apparently an actual test (just read from the third page and scip the mildew shit).
> The dankest strains do come from high altitude areas so could it be more uv or simply more light or even different atmospheric conditions and lower altitude areas seem to have more cbd rich strains, so maybe uva and b are detrimental to cbd ,so many questions and so little tests better get my shit together and start some test journals


Think of light photons as a little ball flying through space. At high altitude the ball has to travel through less clouds and atmospheric particulates so the plant gets more direct sunlight. Just like dawn and dusk... the photon has to shoot across the atmosphere whereas high noon the photon just drops straight through the atmosphere(highest uv concentration)


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## BobCajun (Mar 21, 2016)

Rayne said:


> If you want the plant to develop to it's fullest genetic potiential. UV A/B light and Infrared light must be included.
> 
> Outdoor Sativa strains get bathed in UV A/B plus infrared red and still grow at least 10 foot tall.


I was actually wrong when I said UV-B would reduce growth. Apparently Cannnabis is immune to it, due to the cannabinoids. Here's the article.


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## DankaDank (Mar 21, 2016)

Greenthumbs21 said:


> Think of light photons as a little ball flying through space. At high altitude the ball has to travel through less clouds and atmospheric particulates so the plant gets more direct sunlight. Just like dawn and dusk... the photon has to shoot across the atmosphere whereas high noon the photon just drops straight through the atmosphere(highest uv concentration)


Thats actually how i think of it as well lol, but sub 400 nm photons are not the only photons to loss energy from distance so therefore theoretically there is more light (not just uv) at higher altitudes.


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## ~CReePeR~ (Mar 30, 2016)

OK so I purchased 2x26w 10.0 Desert Reptbulbs. Here are my results.

My setup was 16 Hydro Buckets 8 on 1 side and 8 on the other all running off the same reservoir. Each side had 2x1200 watt LED and 1x800 watt COB. Basically both sides were exactly the same. 1 Side had the 2 UVB Bulbs hanging vert about 8-10 inches from plants
I noticed no increase in trichomes on the side with the UVB bulbs.
But when I harvested I noticed a huge sticky resin increase while I was trimming the plants closest to the UVB Lights

So I figure the resin increase was due to the UVB. A Bonus if you make BHO from your bud.


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## Greenthumbs21 (Mar 30, 2016)

~CReePeR~ said:


> OK so I purchased 2x26w 10.0 Desert Reptbulbs. Here are my results.
> 
> My setup was 16 Hydro Buckets 8 on 1 side and 8 on the other all running off the same reservoir. Each side had 2x1200 watt LED and 1x800 watt COB. Basically both sides were exactly the same. 1 Side had the 2 UVB Bulbs hanging vert about 8-10 inches from plants
> I noticed no increase in trichomes on the side with the UVB bulbs.
> ...


They are technically for supplementing hps with low nanometers. .. your leds already have lower nanometers and some have built in uvb.


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## BobCajun (May 10, 2016)

DankaDank said:


> Im a bit conflicted regarding this topic, this reddit thread seems to make sense https://www.reddit.com/r/Head2HeadMG/comments/2nt3ml/red_white_blue_full_spectrum_an_led_color_choice/
> but then there's this
> http://medicalmarijuanagrowing.blogspot.co.uk/ wich is apparently an actual test (just read from the third page and scip the mildew shit).
> The dankest strains do come from high altitude areas so could it be more uv or simply more light or even different atmospheric conditions and lower altitude areas seem to have more cbd rich strains, so maybe uva and b are detrimental to cbd ,so many questions and so little tests better get my shit together and start some test journals


Good links. So red LEDs around 620-630 nm are cheap and efficient. Makes sense to use mostly them then and only a few whites or blues.

In the UV blog post it's odd that it says CFL UV bulbs don't work, because I've seen the fluorescent tubes he uses (in his YT vids) and the intensity they put out is very low. They have to be no more than a couple inches away whereas the CFLs have the same intensity several inches away.


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## RM3 (May 10, 2016)

I run UV thru out, including seedlings just like outside and have for years. I also flower with T5's so I can alter the ratio of the spectrum to see the effects and I can tell you after years of doing this that ,,,,,,,,,,,,

Deep blue grows/increases trics not UV

UV increases potency 

1st pic, one week old seedling, 2nd pic same seedling week 2
.


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## RM3 (May 10, 2016)

UV also matures the trics faster, here is a bud at 6 and half weeks
.clic to zoom and see the amber


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## Rrog (May 10, 2016)

Cannabinoids don't lend UV resistance. While Cannabinoids may increase due to exposure to UV, that's not to protect it from UV.


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## BobCajun (May 10, 2016)

RM3 said:


> UV also matures the trics faster, here is a bud at 6 and half weeks
> .clic to zoom and see the amber
> View attachment 3678148


As can be seen from the pics, if you use UV the whole life of the plant from seedling the leaves won't get browning on the margins like they will if you only hit them later.

For those who deny that UV-B increases THC, this is a pretty definitive article, though admittedly only using 2 strains. In fact, it not only increased THC in buds but also in leaves. The UV also had no negative effect on growth, as it does in many other plants. Seems to be no downside. 

Also interesting how graphs show increase in growth pretty much flatlines after about 900 PPFD.


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## Greenthumbs21 (May 10, 2016)

BobCajun said:


> As can be seen from the pics, if you use UV the whole life of the plant from seedling the leaves won't get browning on the margins like they will if you only hit them later.
> 
> For those who deny that UV-B increases THC, this is a pretty definitive article, though admittedly only using 2 strains. In fact, it not only increased THC in buds but also in leaves. The UV also had no negative effect on growth, as it does in many other plants. Seems to be no downside.
> 
> Also interesting how graphs show increase in growth pretty much flatlines after about 900 PPFD.


The only possible downside is in the genetics and cloning. Uvb and c cause a bulge in the DNA helix. So if you clone over and over you may get drift or problems but thats about it. It definitely increases potency and changes the chemical make up of the trich. The cuticle on the trich is expanded for more protection


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## toaster struedel (May 10, 2016)

RM3 said:


> UV also matures the trics faster, here is a bud at 6 and half weeks
> .clic to zoom and see the amber
> View attachment 3678148


You using HO or VHO t5s? What's your take on the hortilux eye power veg bulb fs + uv? I'm thinking of running 2 on the ends of my 4 bulb t5s. And any scoop on their other bulbs 633 and 660 I think. Can't find them any where.
http://www.eyehortilux.com/products/power-veg.aspx


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## BobCajun (May 10, 2016)

Greenthumbs21 said:


> The only possible downside is in the genetics and cloning. Uvb and c cause a bulge in the DNA helix. So if you clone over and over you may get drift or problems but thats about it. It definitely increases potency and changes the chemical make up of the trich. The cuticle on the trich is expanded for more protection


I didn't notice any increase in potency when I used reptile CFLs last crop. I put them very close too, like 8", 26 watters, and with aluminum reflectors. I was also using EOD far red so I think that might actually have interfered somehow. This time I'm using them with EOD red. I'll see if that helps. I did read that in some other plants EOD red increased phenylpropanoids by 6%. Things that increase phenylprops would likely also help with THC, since both are "secondary" products. UV is also supposed to increase them. So EOD red may be additive to the UV effect.


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## RM3 (May 10, 2016)

toaster struedel said:


> You using HO or VHO t5s? What's your take on the hortilux eye power veg bulb fs + uv? I'm thinking of running 2 on the ends of my 4 bulb t5s. And any scoop on their other bulbs 600 and 660 I think. Can't find them any where.
> http://www.eyehortilux.com/products/power-veg.aspx


54 watt HO's and no, my next test is gonna be with the agromax line


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## RM3 (May 10, 2016)

BobCajun said:


> I didn't notice any increase in potency when I used reptile CFLs last crop. I put them very close too, like 8", 26 watters, and with aluminum reflectors. I was also using EOD far red so I think that might actually have interfered somehow. This time I'm using them with EOD red. I'll see if that helps. I did read that in some other plants EOD red increased phenylpropanoids by 6%. Things that increase phenylprops would likely also help with THC, since both are "secondary" products. UV is also supposed to increase them. So EOD red may be additive to the UV effect.


I have been saying for years the reptile bulbs have little benefit, have only found a few bulbs that actually work. Had a friend with a UV meter that tested a bunch of em


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## toaster struedel (May 10, 2016)

RM3 said:


> 54 watt HO's and no, my next test is gonna be with the agromax line


i found the fs=uv bulbs at joes hydro for $19 each im gonna try and 420,460,633,660 
http://www.eyehortilux.com/products/powerveg-fs-uv-white.aspx


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## BobCajun (May 10, 2016)

RM3 said:


> 54 watt HO's and no, my next test is gonna be with the agromax line


Here's the output. I thought it was in inches before, which is why I thought it was weaker than the CFLs. Doesn't give the output for closer distances though.






source

Exo-Terra 150





source


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## RM3 (May 10, 2016)

BobCajun said:


> Here's the output. I thought it was in inches before, which is why I thought it was weaker than the CFLs.
> 
> 
> 
> ...


Those numbers look ok, the test he ran was a few years ago


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## BobCajun (May 10, 2016)

RM3 said:


> Those numbers look ok, the test he ran was a few years ago


The figure for 1 foot is no higher than probably outdoors in temperate zones but it must be pretty blistering at 6" or less. With the Exo 150 they'd have to be about 4" away. I didn't have them that close but the reflectors should have helped. The higher version, 200, has twice as much UV but they're hard to find in stock anywhere. I had to take the 150s.


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## Rrog (May 10, 2016)

Greenthumbs21 said:


> Uvb and c cause a bulge in the DNA helix. So if you clone over and over you may get drift or problems but thats about it.


Plants have constant repair mechanisms for UV exposure, including the "bulging" (pyrimidine dimer) you mention. This is a hazard for humans, not so much for plants. 

I suspect the cloning "drift" people describe occasionally as being attributed to the lack of UV over generations, not the exposure to UV. Over the last buncha years, most indoor grows haven't seen much UV at all.


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## Greenthumbs21 (May 10, 2016)

Rrog said:


> Plants have constant repair mechanisms for UV exposure, including the "bulging" (pyrimidine dimer) you mention. This is a hazard for humans, not so much for plants.
> 
> I suspect the cloning "drift" people describe occasionally as being attributed to the lack of UV over generations, not the exposure to UV. Over the last buncha years, most indoor grows haven't seen much UV at all.


I clone under just hps and then add uv in flower. . I and many others ran this plant into i think gen 24... then you have others that have problems after a couple and they have never heard of uv bulbs... i would blame bad clone/grow practice definitely.


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## Rrog (May 10, 2016)

Bad practices won't change DNA or gene expression. You need long term threatening environmental pressures to turn genes on and off, generally. Like heat to create the expression of heat shock proteins. Likely something similar with drought, etc. but these are temporary expressions. 

This genetic drift described lasts, and I'm not sure is reversible. My inclination is that the lack of UV over generations of a clone might turn a gene on or off. Sometimes. On some strains. Central to this is the testimony that the negative traits are not seen on the same strain raised outside. That's very telling


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