UVb an experiment

[Weezard]

Thanks 'shake,
I'm real happy how the little guy is turning out!

Yo Dutch',
Now that's what I like to see, a family that has gone green!

Wish I'd said dat.:thumbsup:

OT:
I've been doing alot of thinking and reseaching about this last experiment. I really want a good light spectrum analyzer for Chistmas, it would make my life much easier.
I now understand why so many scientific light grow experiments (done by real scientists) used/use filters to get or limit light spectrums.

From what I can find, Pyrex tends to absorb light from 10nm to abt 425nm, which covers all three UV bands plus most violet. So chambers 2 & 3 having a 6500k CFL inside the pyrex cool tube surely saw blue light for thier entire vegative stage and chamber 2 (the control w/no UVb) saw blue thru-out it's grow. The fact that I was able to control plant stretch (w/o far red) even tho the light was primarily HPS, I attribute to the additional blue from the CFLs. I have not been able to find or obtain a spectrum graph for the "Zilla desert 50 UVb" bulbs, but the desert 50 refers to the fact that the bulbs will deliver 50 micro watts per second/cm2 of UVb.

So I thinks, no conclude, that the results show UVb effects and not effects of blue light.

Now, that makes me go hmmmm.
50 microwatts per second, per square centimeter?!
And it was how far from the plants?

Granted that UV is high energy radiation but, that still sounds feeble!

Hey KNNA, can you translate this for us?

Dunno how to quantify it properly, or even understand the numbers given, but I'd like to lay your li'l Zilla on an EPROM and see how long it takes it to "lose it's mind".
That would give me some idea of it's actual energy.

My 4' quartz tube can erase 50 EPROMs at a time, from a height of 3" in under 10 minutes.
Sunlight takes more like hours and varies with the UV index.

OK, now I'd love to kick this around somemore with some of the "blue man troops", or anybody else who has any "bright" ideas. (I made a pun....geez I crack myself up).
OM

You crack us all up OM.
An' looks like ya got lotsa "cute" in yer genes too.

Here's a thought.

How fast does that pup darken a "transitions" lens from say, 24" away?
And how does that compare to noonday sun on a clear n sunny day?
Now it's yer turn to carry the rhyme, that is, if you'd care to play?

Sweet pups,
Wee

That'l be one wooden nickel, please

[knna]

Hey, oldmac, congrats on your great grandsond :thumbsup:. Some good pot and a great grandsome is the recipe for the best Sunday morning! (well, probably still great without the pot :stoned

Weez, its difficult to say the total emission from a data of irradiance. 50microwatts/cm2 would equal to 500mW (0.5W)/m2, that is a good irradiance for UVB. But without knowing how far is the lamp on the measurement, or the coverare at such irradiance, its difficult ot say if its high or low. Areas exposed to 0.5W/m2 of UVB are receiving a very good dose (level of tropical high areas if I dont remember bad), but we dont know how big is that spot. Likely the average UV-B irradiance on the grow area was lower. But in theory, with 0.2W/m2 effect should be noticiable.

Im kinda surprised for your results, oldmac. Not about quality effects, but about gross production. Although Ive seen conflictive results with UVB experiments, a clear improvement of dry weight with UVB treatment (from veg!) is something I havent seen before.

Although I havent planned to experiment with UVB, you give food for thought with your results. Unfortunately my spectrorradiometer dont cover UVB range, its VIS-NIR. I feel UVB result are strongly dependent of actual wavelenght (I believe radiation starting about 285-290nm is required) and dosage (I believe same spectrum may vary in effect at different dosages).

Anyway, very interesting. I note that from now on, if I want ot use UVB suplementation, ill do it on veg too.

PD: I agree results are due UVB. On some biological effect, UVB works on same direction than blue, but on others works on the opposite direction.

I forgot to make a question, what was the humidity level?

[Weezard]

" 50microwatts/cm2 would equal to 500mW (0.5W)/m2, that is a good irradiance for UVB"

Wait, what!?
Now I'm truly bumfuzzled.

.5W = Half a Watt = 500 mw
.05W
.005W
.0005W
.00005W = 50 MicroWatts = .05 mw

How will .00005W per square centimeter become a half a Watt per square meter.
Where does the extra energy come from?
This make no sense to me.

What am I missing?

Aloha.
Puzzled lizard brain.

[oldmac]

@ Headshake; thanks for the heads up on the foxit reader. I'm going to give it a try. Not sure abt the web crawler tho, my last computer had something happen in that department, long story....but I bought a new one. It cost me the same price as fixing the old one was going to be and I was not cool on having someone I did not know well, seeing the shit on it.

@ Dutch; I've got a bunch of nickles, but most be made from rock. You say the wooden ones are no good? I think I can plam them off on a little blue 'zard.

@ Weezard; I'm not a ryhmen simon so no thanks trying to respond in prose.
On the pkg for the UVb CFL it states that 50mw spec is at 18". During the entire grow the UVb bulbs were kept right abt 12" above the plants. Check out the second chart that 'shake posted, it gives some UV index "ballparks". BTW I think that graph with it is from a T5 type not a CFL. It made me look at the cardboard sleeve from the bulbs I use, T5 24" 14watt NO (of course I use an IceCap ballast and get 40w each ). But it states the 50mw spec is at 12". Heaven only knows what the heck the output for SHO are and I use 4 of them but I only run them 3 hrs per day, during the middle of the photoperiod. High noon!, taking a page from the "emulate nature" crowd. .
I tried to time the "transitions" at 18" from the light and then oustide but could not. I could never tell when they had reached peak darkness to stop the clock. But it was slower then outside, so I just guessed at it. It really was the reason I decided to run it the entire photoperiod. Maybe I should go hi-tech and check out eraseing Eproms.

@ knna; a little mj goes with anything, anytime. The greatest part with playing with my ggson is if he gets fussy I can him him to his mom and say "see ya later".
As I just said to weez, that spec is at 18" and we kept the light at abt a foot (1/3 of a meter?). The plants were rotated in the tray daily to keep outer and inner rows pretty equal over the grow. Humidity was 50-55% during veg and solid 40% during flower. The grow was conducted in an air-conditioned space, so it was easier to regulate the 3 chambers. The weight increase did not surprise me that much. I have seen a scientific paper that showed increase green mass from UVb supplemation, so if you increase the green wieght of the buds the dry weight follows. Like I said it was not much, I took the average plant weight from each chamber and compared. The least increase was from the "apricot" at 2gr and the biggest difference was the HinduKush (which is not a heavy producer normally for me) at 5gr. Plants were vegged when the tallest was 12" and shortest 10", strains were consistent the variation was between strains. I wish I could get all strains to grow the same, it would be much easier. Finished hgts ranged from 25" to 34".
Oh, OH as I wright this I think the little blue lizard found a fly in your ointment or math. That's why I just guess at shit, run the experiment and can't really quantify the amounts of UVb used. :thumbsup:

[Dutch Pimp]

since my 6500k HO T5's might be throwing off UVB?...(I should hijack this thread)..I mean, contribute to this thread...

I'll update in 4 months....:wtf:...imp:...:smokin:

[knna]

As I said, irradiance data is not enough to know the absolute emission of the lamps, that is which we want to know.

The 0.5W/m2 is a direct conversion from 50uW/cm2. There is 10000cm2 on a m2, so its 500000uW/m2=500mW/m2 (1mW=1000uW).

In general, for experiments Im interested in both irradiances obtained at top plans and the absolute emission, because it allows to calculate the average dosage along all the grow. At 12" instead of 18" irradiance below the buld for sure was over 0.5W/m2, which is a high dosage, specially when used along all the photoperiod (in Nature, UV irradiance drops a lot at sunrise and sunset, the high peak irradiance is just around the noon hours). But if we think on the average dosage of UVB along all the grow, I think that was way lower than those 0.5W/m2 (perhaps 1W/m2). But as it was provided for 18 and 12h a day, UVB dosage along the day probably was significative enough to notice the effect.

But anyway, impossible to say any accurate figure. So lets let it as a significant UVB dosage, but for sure not excessive, give or take in line with outdoor irradiance per day on tropical areas.

Thank for the info, oldmac, I suspected an higher humidity during flowering. But 40% is right.

As for the increase in gross matter, its a conflictive topic. Ive seen too studies showing a role of UVB stopping, inhibiting or delaying growth, but usually those effects appear at high irradiances. Sure that one of the most known effects of UVB is to promote thicker leaves (heavier) and compact plants (say, like extreme sun adpatation), but that it results on a overall increase on weight depends of other factors aswell (compact plants with thicker leaves increase production on crowded spaces and/or lit at high irradiances). Especially when combined with strong green-yellow spectrums, that are way better used by thick leaves, while thin leaves uses better red/blue dominant spectrums.

So of course that is possible to increase overall weight when adding UVB, but for my research (and no practice, so put a grain of salt), it just happen of very specific conditions. Anyway, in your case it was the case, and as the general setup can be considered as very typical, we can conclude that many indoors growers could benefit of it.

But I think its going to be required to check if happen the same when using LED lighting rich on red and blue instead of HPS as main lighting (not for crowded spaces, almost everybody grows so indoors). Not only because the spectrum, but because the average irradiance, in general with LED lighting average irradiance is way lower than when using HIDs, and both factors plays against the benefit of thicker leaves.

[Rusty Trichome]

Hmm...apparently I got lost somewhere...

Usually I promote listening to those that have been there before, to offer insight you might not have already had. But in this case I'm afraid that this is a way to skew results before the experiment even starts. Before using someone else's insight, perhaps use your own insight, and avoid the 'misunderstanding' or ego-driven results of someone elsewhere looking for different results. Were they looking to add bulk, increase trichome glandular head mass, trichome spacing or capitulate stalk length to glandular head mass ratios, trichome degredation (the ambering of the trichomes)...? And does this jive with what we are looking for? (other's insight might be a hinderance to actual positive results)

Until it is known which wavelength works best, why are we worrying about intensity? Doesn't matter how many microwatts per square meter, if the wavelength is off.

Perhaps I'm being too analytical, but shouldn't we find-out which wavelength is best, and which bulbs offer this wavelength, then determine distance, strength and schedule of the winner? Otherwise, we're throwing a quiver of darts at an unknown quantity and trying to determine qualitative results.

I've tried experimenting with Dual Actinics before, but were ineffective at any distance or schedule. Perhaps they were insufficient intensity, or perhaps it was the wavelength...but they are still out in my garage in a box waiting for our next garage sale.

Direct exposure does seem to 'harden-up' the fans and some of the other leaves, but only if in a 'line-of-sight exposure. Reflected UVB does no good. But what good are thick, heavy fans...if it doesn't bulk-up the rest of the "usable" bud? Degredation of the trichomes is the reason I've worked with the UV range, not bulk. But likely that's just me. :jointsmile:

[Weezard]

Hmm...apparently I got lost somewhere...

Usually I promote listening to those that have been there before, to offer insight you might not have already had. But in this case I'm afraid that this is a way to skew results before the experiment even starts. Before using someone else's insight, perhaps use your own insight, and avoid the 'misunderstanding' or ego-driven results of someone elsewhere looking for different results. Were they looking to add bulk, increase trichome glandular head mass, trichome spacing or capitulate stalk length to glandular head mass ratios, trichome degredation (the ambering of the trichomes)...? And does this jive with what we are looking for? (other's insight might be a hinderance to actual positive results)

Until it is known which wavelength works best, why are we worrying about intensity? Doesn't matter how many microwatts per square meter, if the wavelength is off.

It does matter RT.

Consider the bandwith effect.
Even with LEDs the frequency stated is the center frequency.
Intesity falls off from the peak but not precipitously.
An' LED that peaks at 625nm. still has usable output at 652nm.
From CO2 absorbtion we know which wavelength are used to best advantage.
So, we must factor intensity, especially in the high energy range.

We also know that plants can and do convert off-band light to something more palatable (which does serve to cloud the issue.)
Thats why they started out with a "handfull of darts".
That got us to this point.

We actually have the bandwidth issue fairly well sorted.
It's the UVB n C that intrigue me.
Most effective peak seems to be ~285nm.
What I have found, from poking around, is inconclusive.
And I truly do lack the discipline and training it takes to figure it out in my head.

Got the equipment, but lack in disposition of a true science guy.

Oldmac is generating data for my greedy mind.
So, I'm glued to this thread, ferreting out pearls.

When something he finds, makes me go hmmm, I'll jump all over it.
If it shoots one of my guesses down, well, yeeha!
The game is then, afoot, yah?
Gives us a new direction to poke things in.
Saves me from "what I know", that "just ain't so."

Ainokea much about da "kill".
It's the "hunt" that fulfills me.

Perhaps I'm being too analytical, but shouldn't we find-out which wavelength is best, and which bulbs offer this wavelength, then determine distance, strength and schedule of the winner? :thumbsup:
Otherwise, we're throwing a quiver of darts at an unknown quantity and trying to determine qualitative results.

I've tried experimenting with Dual Actinics before, but were ineffective at any distance or schedule. Perhaps they were insufficient intensity, or perhaps it was the wavelength...but they are still out in my garage in a box waiting for our next garage sale.

Direct exposure does seem to 'harden-up' the fans and some of the other leaves, but only if in a 'line-of-sight exposure. Reflected UVB does no good. But what good are thick, heavy fans...if it doesn't bulk-up the rest of the "usable" bud? Degredation of the trichomes is the reason I've worked with the UV range, not bulk. But likely that's just me. :jointsmile:

Nope. 'sme too.
I was questioning the intensity for just that reason.
The experiment is more meaningful to me if we at least match "outdoor" levels.
Below solar intensity level UV., does not really test for degradation.

@ KNNA
Mahalo!
Still seems counter-intuitive to me, but I'll take your word for it.
And, I may have come up with a way to "redneck quantify" UV intensity.:rastasmoke:

Behold, the humble radiometer

[attachment=o258876]

I'll stick it inna box, yank a 285nm. filter from my "rock light" and measure the rpm of noonday sun through the filter.

Then, I'll fire up the quartz tubes and run it through the same filter.
Then, adjust the distance untill we match speed.
That will give me the close-up limit.

Measureing the sun again for morning/evening levels, will give me the distance limit for that light source.
Sound like a plan?

Aloha.
Semi-feral gecko:stoned:

[oldmac]

since my 6500k HO T5's might be throwing off UVB?...(I should hijack this thread)..I mean, contribute to this thread...

I'll update in 4 months....:wtf:...imp:...:smokin:

I'm not sure you could hijack this thread with a gun. I realized when I answered Dog the other day this thread is now over 1yr3mo old (and has had 8,906 views) and seems to have legs of it's own. Heck I was away for more then 3 months this summer and when I was catching up with reading I realized that lively debate and exchange of ideas continued. And that's what these forums should be abt. BTW even without a good Mod like Stinky around some of us really can keep it civil. (but with me that's subject to change w/o notice)

Did you try the "transition" eyewear test or are you just guessing? Whitchever, look forward to seeing your results, your always welcome on my porch.
OM

[oldmac]

Hey Rusty,
I'm with you from the standpoint of find the right wavelenght then worry abt intensity. The reason I used the reptile bulb was I knew for sure there is UVb in it. But I'm also mindfull it has UVa and probably violet and both might have some effect. Heck Weezard is using a 285nm light source which puts it almost at UVc, so maybe close counts.

I have a bit more to say here but need to break off for my dinner, be back shortly.