# UVB for full 12 hours during flowering



## hempknightt (Jan 30, 2012)

I know theres like 2 threads about UVB light already but I couldnt find them... So im just gonna start a new one. Any reason why people recommend not having them on for the whole 12 hours during flowering? Its much easier for me to keep them on with my other lights rather then having them on there own timer that might get fucked up and stay on during my night hours, but I dont want to do it if its gonna be bad for my babiessss. Thoughts? Please share.


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## Detroit J420 (Jan 30, 2012)

be careful with uvb, i use 2 60 watt zoo mega rays and ive turned some indicas into a hardcore amber herion high. uv rays cause aging, you got uva uv and uvb im no scientist, but the sativas are more tolerent to turning amber, difinatly use them though just dont over do it


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## hempknightt (Jan 30, 2012)

I turn them off when I go into my grow room but thats like 30 mins a day off maybe, so like 11 and a half hours on. Is turning amber supposed to be a bad thing? Isnt it just a normal part of the plants growth? Im growing mostly sativas too


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## Detroit J420 (Jan 30, 2012)

mostly sativas, your good then just watch your trichromes, too much amber isnt good but you shouldnt have that prob.. it doesnt take much uv to piss the bitch off she's gonna be wett and sticky..


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## hempknightt (Jan 31, 2012)

sounds good to me!


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## Bonzo Mendoza (Feb 4, 2012)

Most uvb lights (even the best quality 10% uv ones) emit such low uv energy that it probably is not going to hurt anything unless you have the light closer than 8 inches.

I agree that it is unwise to use more than one hour of uvb in the last two weeks of flowering.


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## BenRound (Feb 4, 2012)

As far as I am concerned turning it off for part of the cycle is silly. Its something like "My plant cant handle 5000 watts of HPS light for the full 12 hours, so I only have them on for part of the cycle" Ahhh OK... so then dont use 5000 watts on one plant, use an appropriate amount for the full cycle.

My LED puts out some UVB (yeah the full 12, baby), but I plan to bump it up some on future grows.


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## Rcb (Feb 4, 2012)

BenRound said:


> As far as I am concerned turning it off for part of the cycle is silly. Its something like "My plant cant handle 5000 watts of HPS light for the full 12 hours, so I only have them on for part of the cycle" Ahhh OK... so then dont use 5000 watts on one plant, use an appropriate amount for the full cycle.
> 
> My LED puts out some UVB (yeah the full 12, baby), but I plan to bump it up some on future grows.


What light do you have?


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## BenRound (Feb 4, 2012)

Rcb said:


> What light do you have?


I have a HTG 135w 7 band. Other LEDs also have UVB, such as the Black Star w/ 6 bands.

Im sure its not much UVB. I have plans on adding some 10% UVB CFLs or perhaps 10% T8s--- that is if I dont get a CMH, which I may because I will soon have a 400w HPS ballast to run it on.


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## Rcb (Feb 4, 2012)

do you know what percent of uvb a cmh has? Also where would one find those t8 bulbs at?
also concerning the time on/off for uvb ii would use them all the time the other lights are on.


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## Bonzo Mendoza (Feb 5, 2012)

Running uvb light when there is alot of resin on the flower tops will degrade the thc. Cannabis resin absorbs uvb light (that is why the Great Grower put it there) to protect the plant tissues.

Cannabinoid resin is marijuana sunblock. 

There is no reason to keep alot of uvb on the plant prior to harvest.

The dude that intends to run uvb for a full 12 hours is just going to cook down large amounts of fresh THC that is exposed to high uv into CBD.


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## JustCoasting (Feb 5, 2012)

hempknightt said:


> I know theres like 2 threads about UVB light already but I couldnt find them... So im just gonna start a new one. Any reason why people recommend not having them on for the whole 12 hours during flowering? Its much easier for me to keep them on with my other lights rather then having them on there own timer that might get fucked up and stay on during my night hours, but I dont want to do it if its gonna be bad for my babiessss. Thoughts? Please share.


I so love your avatar, if I could rep you, I would...


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## alphawolf.hack (Feb 5, 2012)

uv shines from all hid bulbs and the sun all day long


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## hempknightt (Feb 5, 2012)

Yeah i basically figured there is UV all day when growing outside. I guess i just though it might be more concentrated in a bulb or something? Lol


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## FranJan (Feb 5, 2012)

Sorry Ben but Blackstars and HTG have UVA (390 nm) not UVB. If your panel has glass in front of the diodes I doubt it has UVB, since UVB doesn't pass through most glass, plus UVB diodes are xpensive and Blackstars ain't (I own 2 240w). But please if I'm wrong educate me.


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## Phaeton (Feb 6, 2012)

This is a CMH reading.

View attachment 2041457 This is a Reptisun 10 reading.

View attachment 2041461 This is an ArcadiaD3+ reading.

I love the CMH's, they are all I use on top of my veg plants, but they do not provide UVB.

The Arcadia's are T5's and wil cause sunburn. 

200 uw and 300 uw are the min and max at the leaf, arcadias have to be held back 18" while the reptisuns are unable to get close enough.

In nature UV is nondirectional and does not come directly from the sun, plants utilize it much more effectively from the side.


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## alphawolf.hack (Feb 6, 2012)

as usual ther is some cocky know it all newb who has been growing for a year and read couple books. well i used to kinda be like that. but then again i have read thousands of books (not just marijuana growing)

start with google LIGHT SPECTRUM EMITED FROM HID this should give you some handy charts that tell you what percentage of energy is converted in to the different spectrum and heat.mh is about 40% hps is about 5% most is blocked by reflector glass and bulb glass so hps is about nil. mh still will put off about 20% thru the glass.

next your going to want to know the difference between coated bulbs and un-coated. and horticultural and industrial. there are varying differences, but un-coated horticultural and industrial bulbs both give off uv.

please do your research kids. research does not have to directly apply to growing some of the most useful info i have found out about ventilation was from an hvac book 

actually you know what don't give me any rep.


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## Kite High (Feb 6, 2012)

alphawolf.hack said:


> as usual ther is some cocky know it all newb who has been growing for a year and read couple books. well i used to kinda be like that. but then again i have read thousands of books (not just marijuana growing)
> 
> start with google LIGHT SPECTRUM EMITED FROM HID this should give you some handy charts that tell you what percentage of energy is converted in to the different spectrum and heat.mh is about 40% hps is about 5% most is blocked by reflector glass and bulb glass so hps is about nil. mh still will put off about 20% thru the glass.
> 
> ...


well the UVB meter I have shows NO uvb...sorry I read alot as well but will trust my METER more than anything anyone here has to say...go read some more then you will find u r in error...or better yet, get meters and know what you saw and did rather than what you READ


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## Phaeton (Feb 6, 2012)

Damn, I guess it takes all kinds. Ignorant is how we all are born, stupid is deliberate.

Coated, uncoated, industrial, horticultural, even the blacklight disco HID's do not put out UVB in any quantity a plant can detect.
Nothing to argue about, that is what is nice about science. It is, or it isn't.

Note the picture of the UVB meter pointed at the CMH. 1 uw (microwatt). A cloudy day is over 50. A reptisun 10 at 20" puts out 50.
1 is the minimum the meter can read. 200 starts affecting plants. Under 25 has no effect, on people or plants.

I like answering questions and helping folks, but aggresive stupid is irritating.

A full time test budroom for a year helped, but even before that I did not post crap or berate people out of ignorance.


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## alphawolf.hack (Feb 6, 2012)

where do i buy this meter whats is its accuracy, what is its method of measurement?(IR, RF, Laser, ect) tell me these thing and i will buy a uv meter have actually never heard of one maybe your right i am going buy what i have read and what has supposedly been tested by scientists. i guess i could be wrong or your meter off (unlikely even i know this) but there has been research that proves uv is emited from hid bulbs. are we considering all uv or just uvb so does the meter measure only uvb? can we see some results from other hid bulbs? im srry not be aggro but i have read so much on this and for me to be wrong would suck but happens. but then again i hear so much bullshit passed around its not funny i mean look at my avatar nobodys is even reading anymore


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## gargantuanganja (Feb 9, 2012)

I've been doing UVB research every day for a couple of months and from what I understand, the sun puts out about 220 here in texas and I wanted to beat that, but it's practically impossible to find the mW of any UVB lamp that isn't made for snakes and lizards. I'm thinking a tanning light would be a good bet because the reptiles will get hurt if there's a lot of UVB and the reptile lights also put out significant amounts of UVA. I just want UVB; UVA is no good for cannabis. I just bought a light that puts out 1700 microwatts of UVB @ 5" that's made for plant growth, but it took an entire day of calling shitloads of people trying to figure out the wattage and I have no idea what the output would be @ the more reasonable distance of about 18"-36". I'm going to run it for 5hrs per day and I will post some results. Although, I will have no idea if this is an improvement because it is my first grow. 

I also hate know-it-all dickheads, so why don't you stop being one. I'm completely new to this, but even I know HIDs (EVEN metal halides) don't put out SIGNIFICANT UVB. I can't believe you are dumb enough to suggest his meter is wrong and you're right. You read something from a "scientist." Well, fuck me. It must be true. I can't stand people with bad attitudes that insult other people's intelligence when they can't even capitalize letters and use punctuation.


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## Phaeton (Feb 9, 2012)

ArcadiaD3+ T5 HO 12% uvb from http://www.lightyourreptiles.com/ 
 The reading is 122 uw at 29", enough to make a large difference as it is on the full 12 hours, not just noon.


Three (3) Reptisun 10 from Zoo Med
 The reading is 130 at 16", this works for lower buds but does not reach the cola. Arcadia is the choice for overkill.

A high noon reading is not necesarry if the UVB is on all day. 150uw at the leaf is running close to the bottom of the noticable effects range. Anything over 50 helps but you have to know what to look for. A noob can feel the difference at 150, a big difference and the stunting is minimal.

I almost did not come back because of dumb dick, but why let him wreck good information exchange.


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## Perma Baked (Feb 9, 2012)

If you're emitting PURELY uvb what would happen if you were to run it 24/7? Would it affect the photoperiodism because the wavelength is so close to the blue range?


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## alphawolf.hack (Feb 9, 2012)

hey man did alot of reading i was in the wrong. you were right although most horticultural bulbs claim to output uv-a. i was reading about reptiles and they stated that uv rays ar present in hid bulbs but the outer envolope is coated in a chemical to prevent its escape. so i am stupid. im on the same train tho about to order some reptisun 10 25w for both sides of my flowering room. my qusetion is would it be better to do 12 hours or 6 with the uv bulbs? my mh that i did believe but now know isnt putting off uv-b runs for 6 hours alrady to emulate noon. (another question would on 40w 4 foot bulb be better? the room size is 4x2x4)

also the only reaon i believed that hids where putting off uv is logic. because why would a sell horticultural bulb that doesnt provide all of the spectrum it can provide? but i am a stupid cocky asshole who needed told off because i was trying to be too smart when i didnt have the proper info. also srry for questioning your meter although is ran of off whats known as a photodiode or possibly a photocathode


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## LSDreamer (Feb 10, 2012)

Some saying about taking a bigger man to admit when he was wrong, fits here. +rep to both, well handled


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## gargantuanganja (Feb 10, 2012)

Perma Baked said:


> If you're emitting PURELY uvb what would happen if you were to run it 24/7? Would it affect the photoperiodism because the wavelength is so close to the blue range?


I'd say most definitely, but I have yet to find a light that ONLY emits UVB rays. They all spit out at least a bit of UV-A and usually some visible light.


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## gargantuanganja (Feb 10, 2012)

I really have got to get one of those meters. I'm so jealous


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## Phaeton (Feb 10, 2012)

The plants need to eat, pure UVB does not have food value, you can't live on just coffee.
I did try a violet/yellow HID, actually I thought I was on to something and have 9 of them. Their spectrum was 404-440 nm and 590 nm, everything else in the 1-2% range.
 So much violet it looked red to me.
I lost the whole crop. Stupid is as stupid does, I'm not exempt either. That was when I built the test room and started killing them one at a time, cheaper that way.

Then I bought meters.
Then I changed lights.
Then I built a new room with more new lights.

Be sure before you go down this road, be really sure, my new car turned into a growroom. Now I'm on foot.


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## LSDreamer (Feb 10, 2012)

Killer setup brotha, you got a journal or anything setup for your room? If you dont you should take pictures, I am looking to setup my room for UVB next harvest, so I would like to get a nice little head start. Of course I could do the trial and error and waste some money, but ehhhhh


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## lilindian (Feb 12, 2012)

I used an Arcadia D3 12% UVB light for the full 12hrs of my photoperiod on my last grow, plant seemed to love it


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## Elvis1 (Feb 12, 2012)

BlackJack fertilizer has a great primer on lighting and uv light,uv provides cell strength,to put it simply,and what could be wrong with that.


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## Ztelthy (Dec 18, 2012)

^Above is my modified old skool TV Cab.. its running a dimmible 250W Lumatek ballast that kicks back from 250w to 175w to 150w.. I am running a 250W MH 6500K for Veg and a SunMaster Dual spec 250W in Flower. 







^ I bought the above UV-B lamp for that much wanted THC/Resin increase..just wanted to check if this lamp will be fine to use in my setup..and want to hear other peoples opinions if there a better lamp I could use in this Cab?

Many Thanks - ZTELTHY


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## cannawizard (Dec 19, 2012)

*that bulb is good for your SCROG/StealthCab setup  i'd suggest running the uvb with the same time schedule as your HID, imo i don't think you need anything stronger than that 10.0 bulb for a one plant SCROG..

#cheers


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