UV output

[fawkes]

I just ran into a very long thread on another site about sunbrite "tube" LED's. You had thought that UV output of the early devices were producing huge UV output. Is this common for most LED's or just white LED's or is it dependent on manufacturer?

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I just know I just know, before this is over, I'm gonna need a whole lot of serious therapy! Look at my eye twitching.

[evilc66]

It's a common trait of early generation white LEDs, long before high power LEDs came about. You may know this already, but there is no such thing as a "white" LED. A white LED nowadays is a blue die with a phosphor coating. The phosphor just shifts the light further up/down the electromagnetic spectrum. Early white LEDs started life as UV LEDs opposed to blue. This is an approach still used by Chinese manufacturers for small LEDs. When I tested the LEDs that PJR had, I had no way to tell at what wavelength the UV light was being emmited.

[fawkes]

Do the higher power Crees (and similar) emit UV? If so which spectrums? Do we have an understanding of the UV requirement for corals?

[evilc66]

There are no manufacturers of high power white LEDs that use UV dies as a base, so UV output is basically non-existant (phosphors do a good job at shifting the spectrum up from the base wavelength, but not so good at moving down).

As for the UV requirements of corals, I have my theories about it, but nothing proven yet. It is known that certain pigments fluoresce specifically under UV light, and all other forms of light that we use for reefs emmit UV light in varying degrees. For example, most MH lamps have a UV spike right around 365nm, even after UV glass. I have measured this myself. What I'm trying to do is replicate the wavelength and intensity of a known setup (Phoenix 14K in my case) with LEDs.

[fawkes]

Good to know. I am interested in what you learn. It almost seems like Sunbright offer a UV "tube"? Does anyone have any experience with it?

[evilc66]

That's a very new product. I think they are using 385nm LEDs, which could help, but i think may have less of an effect than 365nm. I could be wrong on that. I'm a little nervous about companies like this offering UV options with very little information to back it up. UV usage has always been theoretical, and I'm not aware of anyone doing any long term testing yet.

[Mike]

I have a couple 5w Ledgin 395nm UVA bulbs in my set up. I was reluctant to move any further down without more information. I think UV is important to some degree so I decided to use these without optics. I have been toying with the idea of trying a 365nm small set up with like 5-6 of them on a small rig to test.