10.0 Uvb Light

I flowered with Sunmaster Warm Deluxe (3200K full spectrum)es for two years, no HPS. I didn't like the results I was getting - small buds, less weight, the plants seemed to stretch more than HPS for some reason, wouldn't finish, low potency. I switched back to HPS the first week of December, the SC got around 4 weeks of MH, the NB 3 weeks and the Skunkberry and Skunk around 2 weeks.

The UVB has a very blue light, it changes the grow room to white from HPS yellowish red. It's early yet but from the results I'm getting I don't think MH compares at all with UVB.

.

I always liked about 3:1 HPS:MH.. I preferred the buds closer to the MH actually, but they were smaller/less dense..

it's all in the Kelvin of the light

The reptile sun UVB lights are 10,000 Kelvin
If your going to use MH light just make sure your
bulb has a high enough Kelvin.
If you don't your just wasting your time, and money.

ie Link:http://store.atotlamps.net/servlet/-strse-100/175-W-10,000-kelvin/Detail

topfuel29 said:

it's all in the Kelvin of the light

The reptile sun UVB lights are 10,000 Kelvin
If your going to use MH light just make sure your
bulb has a high enough Kelvin.
If you don't your just wasting your time, and money.

ie Link:http://store.atotlamps.net/servlet/-strse-100/175-W-10,000-kelvin/Detail

Click to expand...

The actual physics of HID and the definition of the Kelvin color actually make that statement kind of sketchy.. 10000K does not mean your peak output wavelength is 290nm, that wouldn't make for a very bright light at all..
But in practice its the best bet since its pretty tough to find output spectrums that range below 400nm or so..

born2killspam said:

The actual physics of HID and the definition of the Kelvin color actually make that statement kind of sketchy.. 10000K does not mean your peak output wavelength is 290nm, that wouldn't make for a very bright light at all..
But in practice its the best bet since its pretty tough to find output spectrums that range below 400nm or so..

Click to expand...

You are correct. Kelvin measurements only are applicable from 1000K to 10,000K based on the color a perfect black body radiator appears at that temperature. This ranges from the reddish orange of candlelight to the dark blue of the sky. Since our bulbs are not perfect black body radiators, their color temperature is always an approximation anyway. Also, since color is a human perception it only applies to the visual spectrum so ultraviolet light cannot have a kelvin rating since it's invisible to our senses.

Our bulbs aren't even close to blackbody radiators! Except perhaps from the heat glow.. Gas discharge light has nothing to do with heat, photons at specific various frequencies are emmitted when electrons make transitions as they pass through the gas mixture..
Heat is a byproduct, and its needed to reduce the breakdown voltage, but like a blow torch, the light from HID lights is not Kelvin black-body related at all.. They don't even try to match a BB curve on the spectrum..

born2killspam said:

Our bulbs aren't even close to blackbody radiators! Except perhaps from the heat glow.. Gas discharge light has nothing to do with heat, photons at specific various frequencies are emmitted when electrons make transitions as they pass through the gas mixture..
Heat is a byproduct, and its needed to reduce the breakdown voltage, but like a blow torch, the light from HID lights is not Kelvin black-body related at all.. They don't even try to match a BB curve on the spectrum..

Click to expand...

I did say that our bulbs are not black body radiators but you are incorrect that they don't try to match the color. What it really means is that if we were to compare the lamp's color to a black body at 6500K, it would appear the same to a human observer. The technically correct term for this is Correlated Color Temperature (CCT) which is defined as the value of the temperature of the black body radiator when the radiator color matches that of the light source. CCT implies a color match to a black body at the specified temperature.
Depending on where the spectrum of the bulb falls along the color chromicity scale the bulb manufacturer will label it with a kelvin color depending on where it falls closest to the black body line you see in that diagram. If you notice, after about 10,000K the line stops at infinity meaning any CCTs over 10,000K are pretty meaningless.

Just like lumens, CCT labels are meaningful only to people and plants only care about whehter they receive the spectrum they require to affect photosynthesis.

I hope we start seeing a trend toward bulb companies measuring and optimizing for PAR or photosynthetically active radiation rather than focusing on a meaningless number (at least for our purposes) like CCT.

That actually is the theory behind LEDs, is that they can deliver the same PAR without wasting energy on unusuable wavelengths. I think the only problem with LEDs right now is finding the right combination and I bet it will require 4 seperate wavelengths not the 2 that are currently being marketed.

Interesting, I just found this link for GE's Lucolux high PAR lamp. It seems they market this to commercial growers. http://www.gelighting.com/eu/resources/literature_library/product_brochures/downloads/Horticulture.pdf

I realize you get the gist of the physics, I just wanted to stress the fact because its vastly misunderstood..
What I was referring to is the difference between the 'apparent' color (Kelvin rating) and the component wavelengths that go into making that apparent color.. The actual spectrum doesn't match a black-body curve of any type at all, and they don't attempt to make it match.. With plant lights they focus the energy to logical transitions for absorbtive wavelengths, and for human lighting they focus on the functional result for our eyes.. I've never seen a single HID spectrum that even eludes to a black-body curve though even when integrated over a large d_lamda like they show on the boxes.. Plant spectrums look almost like the opposite curvature to a BB and human lighting usually has peaks ranged across the visual spectrum..

born2killspam said:

I realize you get the gist of the physics, I just wanted to stress the fact because its vastly misunderstood..
What I was referring to is the difference between the 'apparent' color (Kelvin rating) and the component wavelengths that go into making that apparent color.. The actual spectrum doesn't match a black-body curve of any type at all, and they don't attempt to make it match.. With plant lights they focus the energy to logical transitions for absorbtive wavelengths, and for human lighting they focus on the functional result for our eyes.. I've never seen a single HID spectrum that even eludes to a black-body curve though even when integrated over a large d_lamda like they show on the boxes.. Plant spectrums look almost like the opposite curvature to a BB and human lighting usually has peaks ranged across the visual spectrum..

Click to expand...

I agree it is widely misunderstood but there is some correlation to the talk of needing more 'blue' light (6500K) for vegging vs. the reddish HPS (3300K) and I think that confuses people unless they understand the spectral energy output curves and such. You and I are probably fortunate to be science oriented in this hobby because it can get quite technical in a lot of different areas.

subscribed - IM CONVINCED THIS IS A MISSING KEY!

I like this thread too.. I was going to suggest that you ditch your new thread, and do your work here unless the OP objects..

mindphuk said:

I agree it is widely misunderstood but there is some correlation to the talk of needing more 'blue' light (6500K) for vegging vs. the reddish HPS (3300K) and I think that confuses people unless they understand the spectral energy output curves and such. You and I are probably fortunate to be science oriented in this hobby because it can get quite technical in a lot of different areas.

Click to expand...

I agree, for all the average grower should care, bluer is bluer, redder, is redder when you average everything out.. For a few years now I've been meaning to pull out the text-books and see if I could come up with a an ideal theoretical gas mixture.. But I gotta assume the engineers that designed plant spectrum bulbs are gonnabe better than me..
On the subject of misconceptions though I'll take the opportunity to say to those who havent heard my rant yet that THE HUGEST plant light calculation sin is in comparing rated lumens for MH and HPS.. As far as plants are concerned LUMENS ARE USELESS.. Most HPS bulbs have fairly similar spectrums, so if you're comparing two hps bulbs, lumens pretty much boil down to a scaling factor.. Two MH bulbs might have pretty different spectrums, but in the spirit of not being a tight-ass you can kind of use lumens to scale them too.. But if you're comparing the number of lumens of a MH to an HPS, then the comparison is useless for plants because the spectrums are vastly different, and lumens are a measure of how brightly humans see wavelengths, not plants.. Heck, you can't even really use watts to compare the two.. As far as the number of photons pumped go, I worked it out that 275W HPS probably pumps as much as 400W MH.. Plants measure light in µEinsteins (An Einstein is a mole of photons) correlated to absorbtion efficiency..

iVE JOINED THE CLUB- MY MOST RECENT PURCHASE




UVB Reptile Fluorescent Light Tubes x2

• [FONT=Verdana, Arial, Helvetica, sans-serif]Zoo Med Reptisun 10.0 UVB

• [FONT=Verdana, Arial, Helvetica, sans-serif] (1.5inch diameter x 2 tubes)[/FONT]
• [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]S[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]pecified

• [SIZE=-1] output: up to 15% UVA : 10% UVB[/SIZE][/FONT] [/SIZE][/FONT]

[/SIZE][/FONT]

• Wattage: 20W​
• $15 from ebay​

Some tests out of link above...THOUGHT YOU GUYS WOULD FIND THIS BIT INTERESTING

born2killspam said:

I agree, for all the average grower should care, bluer is bluer, redder, is redder when you average everything out.. For a few years now I've been meaning to pull out the text-books and see if I could come up with a an ideal theoretical gas mixture.. But I gotta assume the engineers that designed plant spectrum bulbs are gonnabe better than me..
On the subject of misconceptions though I'll take the opportunity to say to those who havent heard my rant yet that THE HUGEST plant light calculation sin is in comparing rated lumens for MH and HPS.. As far as plants are concerned LUMENS ARE USELESS.. Most HPS bulbs have fairly similar spectrums, so if you're comparing two hps bulbs, lumens pretty much boil down to a scaling factor.. Two MH bulbs might have pretty different spectrums, but in the spirit of not being a tight-ass you can kind of use lumens to scale them too.. But if you're comparing the number of lumens of a MH to an HPS, then the comparison is useless for plants because the spectrums are vastly different, and lumens are a measure of how brightly humans see wavelengths, not plants.. Heck, you can't even really use watts to compare the two.. As far as the number of photons pumped go, I worked it out that 275W HPS probably pumps as much as 400W MH.. Plants measure light in µEinsteins (An Einstein is a mole of photons) correlated to absorbtion efficiency..

Click to expand...

I wish I knew who coined the phrase, but I think once you tell someone, it becomes hard to forget: "Lumens are for humans".

That measurement that you are talking about is PAR or photosynthetically active radiation. That's why I keep saying we will start to see more bulbs like the one by GE I linked to before, Lucolux High PAR lamp

PSL technology
whats the deal with this light
Superb performance and
high reliability
– GE’s advanced sodium
resistant ceramic helps
eliminate early failures to give
a rated service life of 10,000
hours for the LucaloxTM PSL
products.
– In order to achieve maximum
performance, GE recommends
lamp replacement when the
Rated Service Life is reached.
– The lamps use extra rugged
monolithic arc tubes equipped
with GE Reliable Starting
Technology which provides
continuous high performance.
High xenon-fill gas delivers:
– extra light and PAR
(Photosynthesis Active
Radiation) output.
– more resistance to mains
voltage fluctuations.
Zirconium gettering system
improves PAR maintenance
that drives constant and
uniform plant growth.
The diameter of the frame
wire in the lamp has been
minimised to reduce shading
in the installation without
affecting the robustness of
the lamp.
Monolithic arc tube
construction for durability and
lumen maintenance.
thanks for the link

mindphuk said:

I wish I knew who coined the phrase, but I think once you tell someone, it becomes hard to forget: "Lumens are for humans".

That measurement that you are talking about is PAR or photosynthetically active radiation. That's why I keep saying we will start to see more bulbs like the one by GE I linked to before, Lucolux High PAR lamp

Click to expand...

This is the gear I ended up - mounted horizontal ..buds about 2inch away on one side will rotate... on for 8hrs of the 12.

Today I purchased a ReptiGlo 26w 10.0 CFL. I then read all 26 pages of this thread (probably should have done it the other way around). In some of the links provided (like the GE PAR link) they list UV-B as "deleterious to growth." I realize they are referring to cucumber and tomoato plants, but that is a pretty striking condemnation when compared to the raves of some contributors to this thread.

I am going to run the light for short bursts (half an hour, once or twice a day).

Does anyone know where to find the UVA% and UVB% of this particular brand/bulb? Their website (www.exo-terra.com) isn't all that helpful.

Jerry Garcia said:

Today I purchased a ReptiGlo 26w 10.0 CFL. I then read all 26 pages of this thread (probably should have done it the other way around). In some of the links provided (like the GE PAR link) they list UV-B as "deleterious to growth." I realize they are referring to cucumber and tomoato plants, but that is a pretty striking condemnation when compared to the raves of some contributors to this thread.

I am going to run the light for short bursts (half an hour, once or twice a day).

Does anyone know where to find the UVA% and UVB% of this particular brand/bulb? Their website (www.exo-terra.com) isn't all that helpful.

Click to expand...

Yes it harmful.... we know that and too much sun will kill just about every thing,,, UVA/UVB are going to harm the plant in order to help us balance the chems in OUR favour not the plants.

And you think short burst are best ?? I plan on 8hr light cycles for the last three weeks of flower...........
what stage are you ??

I'm about 2 weeks from germination, so they are still little girls right now, hence I wanted only to supplement them with the UVB now. I contemplated running it for longer as the plant ages, and certainly longer while it is flowering. 6-10 hours still seems like a lot to me, and some have been leaving it on for the full 12/12. Crazy.

In the end, I've learned UVB (and UVA and ESPECIALLY UVC) are not good for me (or my cat who wanders near enough the grow room for it to be a concern). If high concentrations of UVB will tan a human's skin in 15 minutes, I can't imagine subjecting my girlies to much more than that initially. I will certainly work my way up to longer exposures, but I am yet to locate information on the point of diminishing returns for using UVB to grow pot (or anything).

By my flower time, then this thread will be on page 95 and hopefully I will have some more concrete info to go on. I'll keep the thread updated if I find crucial info on this subject.

If the site doesn't have it, then its doubtful anywhere will.. Usually resellers just post data offered by the manufacturer.. Best you can do would be to see if you can find a few spectrums from similar bulbs, and try to peg the common similarities..
As for the dosages, don't decide until you see your results.. eza82 would obviously be able to cut back instantly if he noticed 8hrs UV was torching his plants, but you might be selling the potential a bit short Jerry.. My assumption is that if there is a perfect median unterval between those extremes, it would be stumled upon quicker by starting with longer periods and cutting them back as needed rather than slowly increasing the period as they allow..
Another factor that may affect UV potential (for good or bad) would be the intensity of typical light.. Spectrum proportion can change alot of subtleties as I'm sure eza82 is more than familiar with given the research he's done..