Fairly certain the pink is due, at least in part, to the UV.
6 Likes
How cool! I have a Panama Red that throws purple/pink pistils. It looks amazing in full flower!
3 Likes
Hi,
I have used UV since 1989. With the right spectrum, the potency goes up, no doubt at all in my mind. The UV B is more important than the UV A, but they should both be present. The best results were from some old incandescent tanning bulbs that have been illegal for over 30 years. But there are some good ones around - I am using fluorescents from solacure. They are called Flower Power. But, your yield will be smaller, not larger. To me it is worth it as I don’t care what the yield is.
5 Likes
Hi Northern_Loki,
Very good post. I have never expressed it, but have often wondered about the reason the incadescent bulbs that really improved potency for me, did that. Might they have had some UV C emissions? The bulbs were given to me in 1989 by an electrician friend who said that they had been laying about his shop and had been made illegal because they could cause burning of skin.
1 Like
Huh the ir is 30x stronger on the 10w. Good info! Done a side by side yet? The ir kick is enough to keep me from switching just curious.
Hi Limota,
Standard incadescents probably do not really produce a measurable amount of UVC. UVA and UVB perhaps a small amount.
UV-C can be dangerous. As in, could cause cause blindness type of danger.
Ultraviolet A (UVA) 315–400 Long-wave, black light, not absorbed by the ozone layer: soft UV
Ultraviolet B (UVB) 280–315 Medium-wave, mostly absorbed by the ozone layer: intermediate UV
Ultraviolet C (UVC) 100–280 Short-wave, germicidal, absorbed by the ozone layer and atmosphere: hard UV
You will not generally want to use lamps that produce UVC in an open area. They are too dangerous. They are used for disinfection and can lead to acute and chronic severe burns.
Here is a case where a group of individuals were exposed to UVC for 90 minutes: PP821077-10792006.pdf (346.3 KB)
Tanning bulbs, on the otherhand, are designed to produce namely UVA and UVB radiation:
For the bulbs you have, can you provide a photo of any markings on it?
For UV in general and plants, I do believe there are several benefits. Type and ratio of UV is what we need to figure out.
For the IR we are seeing here, I’d label it as “far red”.
IR has varying definitions as to where that band begins. We know that plants can utilize far red radiation for the Pr - Pfr conversion process out to at least 730nm (see this). The bulk of the energy listed above 700nm for these these lamps will be closer to red/far-red than infrared.
Hence, why we wonder/make claims about whether plants use infrared radiation. The actual definition of where the IR band starts is the problem and it tends to vary some from study to study. Sometimes it starts at 700nm other times is starts at 750nm (DIN), etc…
In fact, I can’t quite recall, I think there may be a study that suggests plants show phytochrome response out to 800nm. I need to re-find that…
1 Like
Not looking for a perfect answer. If you had to guesstimate the percentage of uvb other bulbs put out like the graph you listed what’d you say? 0.8%ish? A lot more?
1 Like
Yes, and thank you for the information. I am versed in UV light. The incandescents I was referring to were tanning lamps, and very strong ones at that. But they only lasted for three plus weeks or so when run at twelve hours/daily.
I am more than pleased with the results I’m getting with the solacure fleurescents that are currently in the flower room.
1 Like
Offhand, I do not really know or have the data since there are so many different types of bulbs and technologies.
A couple of thoughts perhaps: the hotter the filament, the more UV (higher energy). The higher the pressure, the more UV.
UV requires rather high energy. It is why UV-C can be damaging to humans and biology. The next level of energy after UV-C is X-Ray and then Gamma rays.
It is this conversion of electrical energy into photons which is difficult and is also why the UV LEDs that exist produce UV in relatively “small” amounts if we were to compare them to LEDs that produce RED, for instance.
For incandescents, we pump the filament with energy producing a white hot filament. The excited filament emits photons and heat as it tries (physics) to maintain a thermodynamic balance with its surroundings (entropy). A portion of these photons will have higher energy than the rest (UV). While the bulk of the photons will be emitted with energies based on the physical properties of the filament and how “hot” it gets. E.g. yup, this is in essence “color temperature”.
So, what this says is that standard incandescent are not high pressure and consist of filaments that can only go so hot. As such, the UV produced is going to be rather low and, if any, it’s going to be UVA. If we switch to halogen, the pressures are much higher and we are likely to see higher energy photons in the UV range. For general halogen bulbs, though, the bulb is doped to absorb this UV energy. So, you’d look for an un-doped quartz halogen lamp to get UV out. Florescent lamps do something from a different angle, we create a high voltage source that transfers energy to mercury (I’m guessing a plasma) which then emits an energetic photon. The emitted photons strike a phosphor coating which then down converts it to heat and a lower energy photon in the visible spectrum. If the coating were removed, we’d see a good amount of UV emitted.
So, sorry, don’t have an good answer off-hand on the amounts of UV for generic lamps since it varies on the type/technique used to create the photons.
This might be of interest as it talks about UV exposure from different type of lamps:
3 Likes
One option to consider is adapting some 10K HID Xenon headlights for their UV-B output. In theory a, 10K xenon bulb should be a pretty good UV-B source. 100 watts of thse type of lights is easily accessible as a 12v kit complete with HID drivers from eBay etc. very cheaply.
All of these type of bulbs have a quartz glass shield that blocks the UV to make them eye and plastic safe, but having had a look at them, think it should be reasonably easy to use a rotary tool with a diamond bit to remove the quartz glass shielding while keeping the bulb itself intact.
It’s highly likely, in fact almost certain that there are other halides in these bulbs rather than pure xenon given how cheap they are, meaning the UV spectrum output will be unpredictable and they likely could contain a significant amount of UV-C. Anyway, for anyone brave/foolhardy enough to try it, this could be a cheap high output source of low heat UV-B, and probably UV-C.
I have a kit and might may have a go at it, but tbh am not sure the UV-C hazard warrants the potential benefits. UV flash burns suck in a big way. 
3 Likes
Hi Northern_Loki,
Thinking back, I am not sure that the tanning bulbs I used were incandescent. Could they have been mercury vapor or halogen? They were shaped like a flood-light - a large flat front, and a tapered neck. When run in the dark the visible light was greenish. What was sure, is that any given strain improved in potency when flowered with the tanning lights compared to without them.
The Xenon light idea sounds excellent. I am going to research to find out more about them.
3 Likes
Migrow has some interesting analysis:
And,
Along with the referenced paper:
uvb-effects-on-photosynthesis-growth-and-cannabinoid-produciton-in-cannabis-sativa.pdf (523.4 KB)
1 Like
I found a reference of the indicative comparison of the spectrum output by the various bulbs if it is of any value to anyone.
Although as I say these plots are only indicative, it is pretty clear that using a xenon arc lamp will require some serious safety precautions. I would be inclined to have it on a separate switch and simply turn it off whenever I was in the room if I had some. It’s also clear that if UV is what you want, Xenon arc is probably the way to go.
3 Likes
Wish that chart kept going. Only shows some of the UVA range, and none of UVB/C.
If you want to get really crazy, deuterium lamps are where it’s at. You could conceivably pull them from old scientific equipment… But high voltage, so know what you’re doing.
For UVA only, you can get LEDs fairly cheap. Those little 3W bulbs are on eBay. I think they have some that go down to 360nm
2 Likes
Oh yeah so it does, my bad 
Here is another one that goes further.
Taken from
https://www.hi-techlamps.com/hamamatsu-l11034-long-life-150w-xenon-lamp/
Seems awfully close to turning your grow space into something like Chernobyl, am not sure I am THAT dedicated tbh
1 Like
Very nice.
This wasn’t covered by Migro’s otherwise excellent analysis.
To me, the sum conclusion is that the three best sources of important THC increasing UV light emitters, that are easily available, are:Exxo Terra 200, Solacure FlowerPower and AgroMax Pure UV.
If anyone should act on using UV supplementation, please protect your eyes!
4 Likes
Sorry for bumping the dead.
Curious what those who’ve gone down this rabbit hole have found. Maximumyield was saying 1-2w/sqft. I was into some heavy sciency reading last night on running it as sunrise/sunset vs fulltime and its effects during each week of flowering. Pretty sure most of it went over my head.
Curious if anyones found some 300nm striplights and tried as side lighting in smaller spaces with it?
1 Like
Did you end up adding any uv bulbs? Looking for some recommendations.
1 Like
No i haven’t done anything with that