Should I add UVB Light?

[Moe.Red]

It's as simple as saying "echo, turn on UVB for X minutes, and I think you are saying X is 50?

Edit posted at the same time. 50 minutes starting now.

Edit Edit - for those just joining in, if we destroy half this tent it's OK as long as we learn something useful from it.

 

[shaganja]

Having done this before and essentially burning the leaves up in the process, I'm trying to understand why my results are different.

How many uW/cm2 should I be expecting for "a pretty good burst?"

Am I being over cautious in listening to the plants?

When use mine, anything closer than 2 ft. Causes burning.

 

[DennisBrown]

Having done this before and essentially burning the leaves up in the process, I'm trying to understand why my results are different.

How many uW/cm2 should I be expecting for "a pretty good burst?"

Am I being over cautious in listening to the plants?

Intensity depends on strain. As far as listening to plants, that is exactly the right thing to do, if you are listening for the right thing. Using any high output lamp (like Flower Power or Agro) you should be able to do 2 hours a day, then you work it up. Typically to 2.5 hours, then 2.75, etc. The key is knowing *when* to listen. It takes about 3-4 days for UV damage to show up. What you will find is the buds that are closest to the bulb, the very tips of the sugar leaves will tilt up if they are getting too much. Back it down. As they grow taller, you might have to back it down some as well. If buds farther from the tops are curling as much or more than the tops, then it isn't UV damage. Using the inverse square law, you can calculate that at 24" from the canopy, a bud that is down 1 foot further is getting about 1/2 the UV (the intensity goes down at the square of the distance, so 2x the distance - 1/4 the power).

The problem with measuring mW/cm2 or whatever measurement you use (we use mW/cm2 for systems, W/m2 for the spectrometer, they all work) is that it doesn't account for the spectrum, and again, 280nm has 100x the burn potential as 320nm, so it's better to dial in for your strain, then measure and use that as a reference. I've seen sativas that can't handle much more than two hours, I've seen indicas that can handle over 8, using the same UVB source. Some say you can work them up to get them to take more UV, but my experience has been that they tend to handle what they handle, and trying to "harden" them isn't very effective. You also don't need to push it to the absolute max, although I have several customers that do this, where the leaves are barely complaining all the time, and they swear it produces more THC but I'm not convinced, and that is kind of outside of what we test for. I use a spectrometer for all my measurements. The cheap hand held meters are fine for some things (we sell them), but they don't actually tell you how much useful UVB you are getting. They are good for measuring you lamps for age, so you can get maximum life, and pitch the bulbs once they go under 70% of original power.

 

[DennisBrown]

When use mine, anything closer than 2 ft. Causes burning.

One other thing: Distance matters. Remember that inverse square law I spoke of? If you put a bulb designed for 24" distance at 6" distance, that isn't 4x the power, that is 16x the power (inversely proportional to the square of the distance). That will fry them. That's why you need the right power level for the distance you are using. We have four different UVB lamps available because of this, plus a 2' bulb.

I'm not sure what lamp you are using, so I can't be certain why yours is burning. Odds are, it is the wrong power for that distance, however.

 

[Milson]

One other thing: Distance matters. Remember that inverse square law I spoke of? If you put a bulb designed for 24" distance at 6" distance, that isn't 4x the power, that is 16x the power (inversely proportional to the square of the distance). That will fry them. That's why you need the right power level for the distance you are using. We have four different UVB lamps available because of this, plus a 2' bulb.

I'm not sure what lamp you are using, so I can't be certain why yours is burning. Odds are, it is the wrong power for that distance, however.

Do you have one table that combines your offerings and which size grow/height is appropriate. I had no idea about your up close offerings and obviously my interest is high and i knew about you and some of your products. Going with one of the universal offerings based on what I have learned today from you.

 

[sshz]

So, I wasn't going to get involved in the thread, as I'd rather spend my time in the room then doing mental work but let's look at the first 4 discrepancies I found between Dennis Brown's comments and Dr. B from Utah State. I'm not saying which is correct cause I don't know, just pointing out the comments which are opposite of each other. There may (and probably will be more) as the thread progresses.

1. Brown says use the entire grow vs. Dr. B says use just last 2-3 weeks for overall plant health.

2. Brown says Indica's handle the UV-B better vs. Dr. B says sativa's handle it much better. Indica's absorb more UV-B because of their larger leaf surface, sativa's skinny leaves are exposed less.

3. Brown says UV-B has little to no impact (3% max) on yield as Dr. B says it can have a larger negative impact over time.

4. Brown says bulbs are the best way for UV-B and Dr. B says UV-B diodes are available (and surely coming) but are very expensive to use so right now it's limited. But prices will fall and then will become more mainstream in fixtures.

Much of what both guys are saying are similar in many ways, but not all. For those who are interested, you can find all of Dr. B.'s videos on Youtube, and I (or others) have posted many of the links in my 3 Gavita threads. I'll again reiterate that Mr. Brown is the owner of a company that sells these bulbs and has motivation to lead you in a certain direction. Dr. B is a professor, who teaches and researches light and it's effects on plants (he has the only U.S. license to use marijuana in his testing facility) for these purposes.

I'm not taking sides either way, I just want to get to the truth. We all want to grow stronger pot, that's the end game. And I hope Dennis doesn't take all this in a negative way, we all appreciate his input and hope to continue the discussion in a meaningful way.

 

[Moe.Red]

 

[Aqua Man]

Wow you take a week off.... welcome to the farm @DennisBrown and thank you for taking the time to get involved and share your experiences and knowledge.

 

[Moshmen]

So, I wasn't going to get involved in the thread, as I'd rather spend my time in the room then doing mental work but let's look at the first 4 discrepancies I found between Dennis Brown's comments and Dr. B from Utah State. I'm not saying which is correct cause I don't know, just pointing out the comments which are opposite of each other. There may (and probably will be more) as the thread progresses.

1. Brown says use the entire grow vs. Dr. B says use just last 2-3 weeks for overall plant health.

2. Brown says Indica's handle the UV-B better vs. Dr. B says sativa's handle it much better. Indica's absorb more UV-B because of their larger leaf surface, sativa's skinny leaves are exposed less.

3. Brown says UV-B has little to no impact (3% max) on yield as Dr. B says it can have a larger negative impact over time.

4. Brown says bulbs are the best way for UV-B and Dr. B says UV-B diodes are available (and surely coming) but are very expensive to use so right now it's limited. But prices will fall and then will become more mainstream in fixtures.

Much of what both guys are saying are similar in many ways, but not all. For those who are interested, you can find all of Dr. B.'s videos on Youtube, and I (or others) have posted many of the links in my 3 Gavita threads. I'll again reiterate that Mr. Brown is the owner of a company that sells these bulbs and has motivation to lead you in a certain direction. Dr. B is a professor, who teaches and researches light and it's effects on plants (he has the only U.S. license to use marijuana in his testing facility) for these purposes.

I'm not taking sides either way, I just want to get to the truth. We all want to grow stronger pot, that's the end game. And I hope Dennis doesn't take all this in a negative way, we all appreciate his input and hope to continue the discussion in a meaningful way.

Well said

 

[shaganja]

There are numerous contradictions from some comments made above and those in Dr. Bruce Bugbee's (Utah St.) video's on uv-b......... I'm not saying which are correct or not, but I found 4 already in a quick read. Take everything with a grain of salt, and do not rely on this one or that one as being correct.

I will say Dr. B has no skin in the game, and has been researching lighting and marijuana specifically for many years, and tends to be the "standard" when it comes to these things. I'm trying to keep an open mind, but it's important to understand everyone's motivation and ulterior motives when posting specific products and claims.

I will say I think each person's personal experience while using UV-B would probably be the best source of relevant info on the subject. Moe is off to a good start, and I'll be introducing UV-B to my room in just a few weeks. So let's not jump to an conclusions just yet, the ship has just left the harbor.

I agree with number two. Our understanding of what indica is, and what sativa is, is incorrect. It isn't as simple as leaf width. My understanding is, plants grown closer to equator, and high elevation has higher resistance to uvb. This can include what we understand as indica and sativa.

 

[DennisBrown]

I agree with number two. Our understanding of what indica is, and what sativa is, is incorrect. It isn't as simple as leaf width. My understanding is, plants grown closer to equator, and high elevation has higher resistance to uvb. This can include what we understand as indica and sativa.

That is correct, but you also have to consider that during the summer, plants grown farther from the equator have longer days, so the net UVB is higher. It is an oversimplification to just say "indicas can handle more" but it is an oversimplification that most people can understand and that works as a "rule of thumb".

As for previous comments as to discrepancies between my claims and the claims of the doc from Utah, my observations are based on a ton of anecdotal information and field tests from thousands of growers over a 20 year period. I would imagine it is a much larger data set. His data is probably more stringently gathered but significantly smaller. It isn't always that one is right and one is wrong, it can often be that there are other circumstances coming into play that one or both of us haven't taken into account. Universities have only recently been able to do any testing without fear of losing federal money, btw. We never had to worry about that, although most of our testing has been doing outside of the law.

Because each strain can be so different in how it reacts to anything (light, uv, nutes, water, etc.) it is very hard to make sweeping generalizations that are 100% correct. We are forced to make generalizations simply because that is what people want, and that information is fairly useful. Also, while he seems to be focused mainly on THC and UVB, our research is a bit broader.

 

[Moe.Red]

We get a new data point today in the form of a TLC test. This measures individual cannabinoids.

I have a startup bud from a center cola of this White Widow (Fem, Greenhouse Seeds) test plant that was taken prior to UV. It has been dried and decarbed. I took a large enough sample to allow for future lab testing if it seems necessary at the end.

This morning I took a sample from the UV side and the control side. It is drying right now. By lunch I will have them dry and decarbed and we can run the test on

Startup bud - prior to test - no UV
Control bud - day 6 of test, no external UVB but UVA is coming from the HPS bulbs (~30uW/cm2)
UV test bud - day 6 with the following exposures:

Day 0 20 mins
Day 1 30 mins
Day 2 40 mins
Day 3 50 mins
Day 4 0 mins
Day 5 50 mins

(2) Solacure Flower Power F40s at 21" on the left half of a 4x8 fallponics hydro with CO2.

Should be interesting.

 

[DennisBrown]

I'm not taking sides either way, I just want to get to the truth. We all want to grow stronger pot, that's the end game. And I hope Dennis doesn't take all this in a negative way, we all appreciate his input and hope to continue the discussion in a meaningful way.

I didn't take it negative at all, there are lots of different sets of data we all work with. I would add that while, yes, at the end of the day, I sell bulbs to make money, that doesn't motivate someone to be "wrong". In fact, there is more at stake for me if I'm grossly wrong. Most of my income is derived from non-cannabis activities, as I design UV products (LED and fluorescent) for UV resin curing, materials aging, pig tanning, and dozens of other uses. That has been beneficial because it helps us with economies of scale, but also because I learn things from one field that can apply to others. The vast majority of our time and money for research goes into cannabis related research, however. The other uses finance the cannabis research, basically.

We also do not get involved in nutrients, soils, general lighting or other aspects of growing. In fact, everything we develop and build is a UV device; UV is all we do, 12 hours a day, 6 days a week. I started with tanning beds almost 30 years ago and branched out from there. I developed most of the products for the SunMaster and Virtual Sun lines of tanning beds, for instance, a brand many people will know. My partner started almost a decade before me. The point being that our experience with UV is broad, yet singularly focused on UV. A good example of how this experience helps is that you don't see us talking about UVB % when comparing products because we know the number is rather useless. It is complicated to explain in a short post, but it is. I can easily make a 10% lamp that will burn you faster than a 20%, for example. This gets into the physics, which most people aren't interested in. They just want results.

 

[Milson]

While i think bruce is a decent guy, he's also selling his apogee meters by shilling the work of his grad students to a niche with extraordinary interest that has been starved of access to scientific knowledge in the field by a seriously imperfect world that targeted this plant for bad reasons. The ROI on those videos has to be great for him!

Let's call a spade a spade. He's not some pure-hearted, just for the science saint. And i have been very enthusiastic about several of his videos!

 

[Moe.Red]

A good example of how this experience helps is that you don't see us talking about UVB % when comparing products because we know the number is rather useless. It is complicated to explain in a short post, but it is. I can easily make a 10% lamp that will burn you faster than a 20%, for example. This gets into the physics, which most people aren't interested in. They just want results.

Along the I just want results line...

I am running your bulbs and fixtures on a plant that you have mentioned by name, everything have been documented and I am still not really getting why my results are so different. I was really hoping you could shed some light on why with specifics. I get the every plant and grow is different thing, but I would think data along the lines of

White Widow at 24" (2uW/cm2 using flower power 4') run at 2 hours per day from flip to harvest impacted the THC by X and did not harm the plant. Or am I expecting too much because gardener impact is more important than the UV?

 

[Moe.Red]

While i think bruce is a decent guy, he's also selling his apogee meters by shilling the work of his grad students to a niche with extraordinary interest that has been starved of access to scientific knowledge in the field by a seriously imperfect world that targeted this plant for bad reasons. The ROI on those videos has to be great for him!

Let's call a spade a spade. He's not some pure-hearted, just for the science saint. And i have been very enthusiastic about several of his videos!

True (hell I run his gear) and also the vast majority of his work was on hemp. When he gets going in the videos, he uses Hemp and drug cannabis pretty much interchangeably, something that always concerned me.

 

[MIMedGrower]

That is correct, but you also have to consider that during the summer, plants grown farther from the equator have longer days, so the net UVB is higher. It is an oversimplification to just say "indicas can handle more" but it is an oversimplification that most people can understand and that works as a "rule of thumb".

As for previous comments as to discrepancies between my claims and the claims of the doc from Utah, my observations are based on a ton of anecdotal information and field tests from thousands of growers over a 20 year period. I would imagine it is a much larger data set. His data is probably more stringently gathered but significantly smaller. It isn't always that one is right and one is wrong, it can often be that there are other circumstances coming into play that one or both of us haven't taken into account. Universities have only recently been able to do any testing without fear of losing federal money, btw. We never had to worry about that, although most of our testing has been doing outside of the law.

Because each strain can be so different in how it reacts to anything (light, uv, nutes, water, etc.) it is very hard to make sweeping generalizations that are 100% correct. We are forced to make generalizations simply because that is what people want, and that information is fairly useful. Also, while he seems to be focused mainly on THC and UVB, our research is a bit broader.

dr. Bugby is sure not focused only on uvb and thc. He is the guy who designed all the new apogee meters to read wider spectrum after discovering the par meters are too narrow for full photosynthetic spectrums. And he is a career agriculture professor. Nutrients and lighting are his specialties.

If you have not seen his work (and your comment says you have not) you should. Your research is to sell products. He has no similar agenda. And he now runs the cannabis lab in the university of Utah. They have many plant chambers conducting experiments. He has a tour video that shows it all.

you said it yourself. You have tons of anecdotal information. I would hope you are interested in peer reviewed studies and properly conducted testing on the subject.

 

[MIMedGrower]

True (hell I run his gear) and also the vast majority of his work was on hemp. When he gets going in the videos, he uses Hemp and drug cannabis pretty much interchangeably, something that always concerned me.

I agree with this but he does say he has consultants in the medical field of cannabis.

He also has many years of plant lighting research well before cannabis or hemp was allowed.

 

[Moe.Red]

I agree with this but he does say he has consultants in the medical field of cannabis.

He also has many years of plant lighting research well before cannabis or hemp was allowed.

I view my job as listening to everyone and reading everything I can on subjects like this that interest me. Separating the wheat from the chaff is both difficult and rewarding as you see it play out before your eyes.

My hope for this thread is to find a result with evidence and shared raw data that peers collectively accept here at the farm. I have no dog in the fight as to the actual result and I am as prepared for it to be negative as positive. Listen to everyone, make decisions about steering the test based on the best possible peer reasoning, and learn something in the result, even if it means we missed the point and need to retest.

I just wish I had legal access years ago to get all this started sooner.

 

[DennisBrown]

dr. Bugby is sure not focused only on uvb and thc. He is the guy who designed all the new apogee meters to read wider spectrum after discovering the par meters are too narrow for full photosynthetic spectrums. And he is a career agriculture professor. Nutrients and lighting are his specialties.

If you have not seen his work (and your comment says you have not) you should. Your research is to sell products. He has no similar agenda. And he now runs the cannabis lab in the university of Utah. They have many plant chambers conducting experiments. He has a tour video that shows it all.

you said it yourself. You have tons of anecdotal information. I would hope you are interested in peer reviewed studies and properly conducted testing on the subject.

We both would like to see more peer review studies. We give away a lot of gear to do small studies. And someone earlier was saying he does sell products, I don't know. And yes, he studies nutrients and the whole agriculture aspect, we don't. We specialize in pure UV research. We do with with Texas A&M and others who use our lamps studying agriculture on the whole and the effects of UV on plants. My bias would be in "my product vs their product". There is no "$x hours works better than $y hours" bias, or "indica can handle more than sativa" bias. Those have no financial bearing on either of us, those are simply data points, drawn from different data.

We do real research (at differing levels of quality) but yes TONS of information is anecdotal, but it is anecdotal based on input from hundreds or thousands of people, not dozens, so even that information has merit. With flu, the same was true for losing your sense of taste and smell. They began saying it was a symptom well before any study was published, because when the anecdotes are that numerous and all agree with each other, the conclusions tend to be valid.