I suppose, as a manufacture of the Vertex Illumina, one should expect any of my comments to be considered biased. Despite this possible perception, let me tell you a bit of the UV story from this side.
First, yes, certain parts of the UV spectrum are interesting for corals. The area around 390-400nm clearly is involved with the maturation of certain GFP into red pigments (kaede pigments). This part of the spectrum has been represented by both T-5s and Halides in variing amounts. As leds were first mature enough (as a technology) to be usefull as aquarium lighting, there were no UV leds available. This is why they are later to arrive on the scene.
(also, just to make it clear, UVA is below 400nm. Above this we are dealing with a violet, a part of the PAR spectrum. PAR is nothing more than the to humans visible electromagnetic spectrum: light! 400nm to about 700nm. Above this we are in the infrared, which we know better as heat)
The first UVA leds were mainly developed for the medical/science industries and had a very high pricetag, making them economically prohibitive for aquariums. Also, their wavelengths were not well researched in relation to corals. The question was, do we need them.
Interestingly, the answer is actually, a partial No! Corals will grow and develope beautiful forms and colours without them. However, and this is the main point of them, certain pigments will no longer develope without certain parts of the UVA to violet spectrum. This has become clearer over the last years as we have researched the reactions of corals to specific parts of the spectrum.
In the end, and here speaking for Vertex, we want to offer the customer a product they can use now and grow with. The original LED array of the Vertex lamps is designed to allow an aquarist to grow wonderfull corals. And it does this. As many of us are never happy with what we have and do wish to push the envelope, as new possibilities become available and meaningfull, Vertex brings them onto the market in a package that the aquarist can pick and choose from. Truly individual lighting possibilities. You would be surprised to know, most aquarists are not interested in having all the latest innovations. They prefer usefull stability. The dyed-in-the-wool marine aquarist is another species altogether. They want to see what can be manipulated, improved, customised, etc. For these people the new, affordable UV to violet led options are of great interest. They can now squeeze a bit more our of the corals.
Time will tell just how much UVA to violet specific corals benefit from. If you look at the attenuation of light in seawater, you will notice that the 410-420nm range is actually the strongest penetrator, reaching 100m and more. Keep in mind, light spectrum is important for pigment developement, as most pigments are actually protecting the corals from too much radiation of that colour. Yes, a red coral is reflecting away excess red radiation. It doesn't want it. This does not mean that red pigment is the result of red light per se, rather that the coral reacts to this light with a production of a specific pigment. This pigment may require 405nm violet to mature to this red! Therefore, red is not the colour to add to get stronger red pigment in most cases (I have to stay open with this statement, as we are always learning more and this part of the puzzle is far from complete). Things are simply not that straight foreward.
I hope this is not too much information. The original question was, is UV a farce. Answer: certainly not! It is another part of the puzzle and the picture is getting more and more complete. As technology moves foreward, so will led lighting technique. LEDs are a welcome paradigm shift in aquarium lighting offering a completely new approach to reefing. Once you work with them, it's like having the glasses clean and really perceiving what light is and what you can do with it.
Jamie
i know your stance on this
