UV LED over tank
 

I'm just curious how many 3W UV LED's (http://www.rapidled.com/violet-uv-3w-led/) people would recommend using based on their own DIY builds these days. My tank is 84" long by 36" wide by 30" deep and will be sps dominant. Thanks for your help.

Consider the following:
http://www.reefs.org/library/talklog...060202/pas.jpg

This can be used as guideline for what corals will actual benefit from in terms of light spectrum. You can see below 400nm corals use very little if any. If you already use royal blues that peak at around 450nm then you probably have the lower spectrum pretty much covered. You could add a few more LEDs in the 425nm peak range, which I wouldn't consider UV leds but rather violet LEDs, just to be sure you've covered that lower section but how many is hard to say without knowing what you're currently using for royal blue. Note that purchasing true UV leds with ultra low wavelength of below 400nm is probably not beneficial to coral growth.

Here's another useful pic
http://i685.photobucket.com/albums/v...mvsCreeXRE.jpg

Note if you can use LEDs that peak at 425nm in 50/50 relation with blue LEDs that peak at 475nm the use of royal blue becomes less important.

I'm not too sure what wavelength my Royal Blues operate at unfortunately but I know that I purchased them from Milad when he did his group buy at the beginning of last year if that helps.

Through Milad, he sells a 3W Exotic True Violet LED that ranges from 390-430nm. I've got a couple to put on my build but haven't had the time to start putting it together yet to tell you what they're like.

I didn't buy my UVs through Milad. Just my Royal Blues.

Sent from my Lumia 800 using Board Express

Milad's ocean coral whites seem to make a lot of coral colours pop. Check out the full spectrum builds on nano reef.

***Disclaimer: Sphelps, I'm not ripping into you here and I am agreeing with you on the set-up. I just need to say something here because it's the same deal with the debate surrounding red and green LEDs, where people whip out the "science" without considering all the science at play. So... This is more of just a general comment and not actually directed at you because everything you said is entirely true.****

For the record UV LEDs don't stimulate coral growth (Sphelps established that well, good on him), so we need to stop the debate whether they are worthwhile or not in that arena. They are almost entirely aesthetic.

What they do do though is stimulate pigmentation in corals. The pigments act as a "sunscreen" to UV and the pigmentation is what makes them pretty to us. UV also causes fluorescence of certain pigments, which will make certain colors of certain corals appear different or more intense. Green and red LEDs cause the same fluorescence in other pigments, which again rounds out the color visually but add little to the actual growth of the coral compared to the overall usage of white and blue LEDs. White LEDs contain more distinct peaks at various wavelengths compared to the well rounded spectral profile of natural light (and to a lesser extent halide lighting), so some auxiliary LEDs are needed/desired to balance out the colors visually.

Lagoon dwelling corals, especially those that are exposed at low tide, do actually receive significant amounts of UV through out the day, so adding UV LEDs can simulate the amounts they would experience in nature. Now, whether adding this UV actually results in increased coloration in captivity or yields a healthier specimen remains to be seen as this is so new (and I mean real results, not just anecdotal).

Now, the LEDs that are marketed as "UV" in the aquarium hobby aren't UV: they're violet. So all the arguments for the benefits of UV go out the window with these LEDs. Again, they're entirely aesthetic. They are an alternative to the super-blue look of the royal blue where you can get that actinic "pop" without making the rest of your tank look like the Blue Man Group. That said, our eyes are very insensitive to this particular wavelength, so all you would really get is a backlight-like pop of certain colors but only when the main LEDs are off as the effect would be entirely drowned out by the intensity of the rest of the LEDs. So Sphelps suggestion of forgoing the "UV" LEDs and mixing 50/50 425nm and 475nm is awesome. You'll probably be getting more of the effect you are looking for.

AND... Having said all that though, I would also like to whole-heatedly encourage you, Jaws, to not listen to a single word us jaded buggers have said and to go out there and just experiment - you may stumble onto something magic that we're all missing. If you can find a few decent UV-Violet LEDs, give them a go. Based on my knowledge of real UV LEDs (which is far too indepth than I would want to admit), placing them every foot or so might do the job. So in your case that would be a 2x6 grid.

And just as a point of reference, a true 3W UV LED would run you anywhere from $50 to $300 a piece (depending on wavelength) and would barely last 5000 hours of operation. I know this because I just order 7 new ones this morning to replace the ones that just burnt out in 1000 hours on my reactor ( I am finishing a PhD where I am using UV light to split water into pure hydrogen and oxygen to make clean fuels... Like I said, way too indepth knowledge).

Sorry for the rant. Ummm, carry on...

thanks for posting that ScubaSteve, now I don't have to type a long one like you did.

It will suffice to say, that I agree with you 100% PAR is only one part of the equation, fluorescence and its manipulation are another. and there are several colors which are activated under 400nm.

Dana Riddle, has written a series of 5 articles on this starting with this one in 2006 http://www.advancedaquarist.com/2006/9/aafeature

there a real good read, and have a lot of info.

now if you don't want particular colors then don't include the activation wave length range in your lights. but if you want them you need to cover quite a range.

Steve

Certainly no expert on lighting but my understanding of UV light is that it relates to spectrum wavelengths. UV-A is in the range of 315-400nm, UV-B in the range of 280-315nm and UV-C in the range of 200-280nm. Ultraviolet light is by definition not visible so a true UV led would not omit visible light however some of the "UV" Leds on the market peak at 380nm so they omit light in both visible and invisible spectrum most of which falls under UV-A so for the purpose of our hobby and application calling these UV leds seems accurate. Any thing above 400nm however is just plain violet despite often referred to as UV.

I'm only aware of LEDs in the upper UV-A range so the damage they can preform from UV radiation is virtually nothing and are completely safe. Lighting like metal halides have much more light found in the UV-A range therefore requiring UV shields to prevent damage. In terms of UV and coral sunscreen, corals found in swallow waters do create there own sunscreen for UV-A and UV-B protection however I wouldn't attempt such things in your aquarium. For many corals this is just a slime coating which in you can actually remove and use for sunscreen if you're ever stranded on a tropical island. I've read some things regarding SPS corals and color pigments but honestly don't know much about it, the article Stricrazy posted looks to very interesting and something I'll certainly look into further if I ever get more involved in SPS again. However my previous experiences have shown there are much more effective ways of reducing zooxanthellae in these corals to better show color pigments and care should be taken when messing around with too much UV light as this may just bleach corals.

Sterilizers use much lower spectrum, typically UV-C as I understand it which would serve no purpose in aquarium lighting. LEDs in this range would certainly be very expensive if even available.

So again I would stick with what I mentioned earlier avoiding anything much lower than 400nm as it does not aid in growth. Using LEDs that peak at 425nm IMO makes the most sense, how many will depend on what other LEDs you're using. When the time comes and you're more interested in coral coloration then you might consider experimenting but there are many other proven methods that will safely increase coloration without changing lighting.

Great information. Thanks guys!

Sent from my Lumia 800 using Board Express