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LED UV grow light Vs Fluorescent UV grow light

UV LEDs Vs UV Fluorescent grow light test

Why are UVB fluorescent fixtures  still the best UV grow light fixtures when there are UVA and UVB diodes available on the market?

To demonstrate the difference in performance I compare a 100 watts LED UV bar grow light and a 20W UV fluorescent grow light for UVB and UVA output.

The LED bar is a 100W, 2 x LED bar package from Mammoth lighting and includes UVB diodes (310nm) and UVA diodes (395nm). There are about 15 UVA diodes to every 1 UVB diode delivering the spectrum output below.

UV LED bar spectrum

Mammoth UV LED bar spectrum


The MIGRO UVB 310 Fluorescent emits a spectrum range from 280nm through UVA and into the PAR range.

Fluorescent UV grow light spectrum

MIGRO 310 UVB spectrum


UVA and UVB grow light tests

I first tested each fixture for UVB output in a 5x5 or 1.5m x 1.5m test area at 40cm hanging height. I used the Solar Meter UVB sensor with a sensitivity range up to 320nm, just before the start of the UVA range.


Solar Meter UVB sensor


The 100W UV LED bar delivers an average of 6µW/cm² over the test area


Mammoth LED UV bar UVB output test


Fluorescent UV grow light emits more UVB than the UV LED grow light

The MIGRO UVB 310 is only 22W consumed but delivers 7 x times more UVB than the LED fixture. The Fluorescent UV grow light is far more efficient and effective than the LED UV grow light.


MIGRO UVB 310 UVB output


The UVB LEDs are only about 1/15th or about 6 to 7 watts of the total output so the UVB output per watt is quite high but the total amount of UVB delivered is low compared to the 22W UVB Fluorescent.

I then tested both fixtures for UVA output using the Apogee SU-200 UVA sensor with the following sensitivity

Apogee Su 200 UVB sensitivity range

The Mammoth LED bar delivers an average UVA output of 576W/M²

Mammoth UVA and UVB LED bar output


The MIGRO UVB 310 emits an average UVA intensity of 217 W/M².


MIGRO UVB310 UVA output


Fluorescent UV grow light emits more UVA than the UV LED grow light

The MIGRO UVB 310 emits about 40% as much UVA as the Mammoth LED bars but only consumes about 20% of the power. Therefore the MIGRO UVB is over twice as efficient in delivering UVA to the plant canopy as the LED bar.

The 100W LED bars cost 2 to 3 times as much as the 20W UV Fluorescent fixtures but are much less efficient. My conclusion is that UVA and UVB LEDs are not yet effective or cheap enough to compete with fluorescent technology.

Buy the MIGRO UVB 310 here



3 thoughts on “LED UV grow light Vs Fluorescent UV grow light


Hi there!
How many tubes should i hang in an 90×90 cm tent? And where would you place it/them (i got a magnificent Aray 3).

I thank you,



June 13, 2023 at 12:59pm

Fast & well-packaged delivery :) From Irland to London 5 days, I Can’t wait to use this product in 2 weeks with my Mars Hydro SP3000 in a 2×4. Big thanks to Shane for sharing his knowledge with the growing community. :)

January 20, 2023 at 09:38am
Laurie Jean Edeburn

Just get one….or more…u can testify the amazing results of both the uvb 310 and love the 4 aray2’s I have as well….
You will be very happy…all u need

May 3, 2022 at 14:48pm

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