UVB Supplemental LED

@dbrn32 @Hellraiser @Covertgrower @Myfriendis410

Has any one had any experience with “Cirrus LED Systems - Reflex-UVB Supplemental LED Grow Bar” ?

Are there other UVB LEDs?


I’ve never used them. Cutter has uvb leds, there are also a few fluorescent options.


Only run uvb 1-2 hours a day to start. It’s excessively stronger than uva. Up over 100x. Then uvc just blows those numbers away. At the utah university on uvc tests more than 4-10 minutes a day would cause more harm than good. 1-4 hours for uvb. You can run uva all day.

Technically greenhouses only allow uva through, block virtually all uvb. It’s uvb and uvc that burn you too. Not uva.

When I feel my grow is dialed in enough to add uv I will add only uva. If you aren’t already breaking 1g/w on harvest. UV isn’t gonna be beneficial to you anyway.


Oh yeah, also. Forgot till now, wait until a few weeks old before turning the UV on too. Unless you’re using it purely for sanitation purposes. Plants born under the sun cannot use uv rays for photosynthesis, plants that get big enough to handle UV before ever seeing UV. Actually can use UV for photosynthesis. If a plant is born under UV, like from the sun, it’ll harden itself to UV completely. Since it would kill the seedling otherwise. So if you sprout a plant under UV. It won’t be able to utilize those powerful photons. Oh. And for sterilization, for when I’ve seen it actually work. It takes about 20 minutes of uvc at 5w in a 3"x3"x2". It was a pacifier sterilizer that used uvc for a period long enough to burn you if you were inside that pacifier box. The biggest thing about uv is that they are super powered photons. And they have the potential to add massive amounts of photosynthetic in a miniscule amount of time with a miniscule amount of energy. And if some still really wonder about how those outdoor monsters who get a month or two headstart just be… well… monsters. Is because since they didn’t see the sun the first month. And where introduced slowly. They are now using these highly powerful and excitable uv rays for photosynthesis. I don’t know why I wrote all that when I could’ve and still am just gonna drop this.

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@Budz I have the UVA30 attached to my 600R rspec. I also have two 2 ft uvb fluorescent bulbs on either side of the 600R in my tent at the same height. I run the uva the full 12 hours (7am-7pm) with the rspec, the two uvbs I run 8 hours (9am-5pm).

The issue i have is supposedly the fluorescent bulbs must be replaced each year +/-. I like that LEDs give you 50,000 hours +/-. Plus they are less delicate.

The only 2ft-4ft LED UVB grow light bars I can find are the 4ft Cirrus Reflex UVB bar. However, they seem to have discontinued their grow lights. So originally they were $599. I found them for $199 and thought of buying two to replace the fluorescent bulbs and fixtures.

@dbrn32 I can’t seem to find the Cutter. Is it do it your self stuff?

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No experience with UVB LEDs.



How are these specs:

" The horticultural LED Reflex UVB is the perfect lighting that can be added to a HID, HPS and LED lamp.

This bar has 56 LEDs and a lighting angle of 120 °.

Made of aluminum, this light has a lifespan of 50,000h and a 2 year warranty.

Data sheet

LEDs power 168W
Power consumption 105W
HPS or MH equivalent 240W
Coverage area 200cm x 45cm
Spectrum Blue 430nm
Lens angle 1200
Plug & Play No
Mobile app No
Thermal management Passive - Completely silent
Daisy chain No
Wifi No
Zero noise Yes
Waterproof Yes
Lifetime 50 000h
Size 120cm x 7,6cm x 9cm
Manufacturer’s Warranty 2 years
Lighting type LED Ramps
Use Intensive Culture
Power Between 100W and 200W

" This Reflex UVB bar from Cirrus Led Systems won a High Times competition in 2016. It increases the production of resins by 28%."

Is it just me or do the specs list the spectrum at 430nm?

Isn’t that above uva?

Uva - 320-400
Uvb - 290–320
Uvc - 100-290

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Yep, specs don’t match the spectrum chart and the spectrum chart shows a tiny bit of UVB and a lot more UVA.


I agree, 430nm isn’t uvb. I don’t know what the issue is but I would investigate further before buying anything.


@dbrn32 If I wanted to buy parts to build a uvb led setup where would I find them?

Is it as simple as mounting the chips to a heatsink, wiring them in series or parallel, add a driver… And done?

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That is what cutter electronics sells. You would have to see what he has in stock, and parts come from Australia. But he typically has individual leds on 20mm stars and linear modules with multiple leds, like a strip.

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