Thought on UV LED

[Reeferside]

So for those of you guys who utilize LED systems that incorporate UV technology/lights, what are your thoughts? Is there noticeable difference/benefits that you associate with the presence of this type of spectrum?

Also.. does purple light in T5 lighting contain UV spectrum/wave lengths? I a bit confused as to what consist or is categorized as UV lighting. Does this only exist in LEDs or can this be achieved with halides and T5.

I'm running 8 bulb T5 ATI unit. Just ordered 2 all blue XHO Reef Brites. Thinking about adding an additional UV LED bar from Build my LED. What are your thoughts?

 

[dartier]

The definition of UV are wavelengths <400nm. Wavelengths between 400-430nm are considered to be Violet light.

I can't speak to the benefits just yet as I am just in the process of moving to Kessil AP700 units that do incorporate UV (380nm). The AP700 is one of the few LED units that do incorporate UV in their spectrum.

I personally feel that UV is an important part of the spectrum (in moderation) and is lacking in most LED lights. Both T5 and Halide produce UV spikes around 380-390nm, and this spectrum has been shown to provide significant Photosynthetic Usable Radiation (PUR) for corals.

My hunch is that UV light may help corals to maintain their colors, but time will tell.

Dennis

 

[Ron Reefman]

I can agree with what dartier said.

My 3 year old leds only have 420nm violet (which they called UV and it isn't). But then most led fixture companies do the same thing. I had 4 250 watt MH and 4 39 watt t5 before I switched to leds. I can't say that the MH/t5 fixture made for better color in the coral than the leds. But the leds do allow for making the system much more blue and does cause better fluorescing colors than the MH/t5.

Whether true UV will help corals is very questionable. UV spectrum just doesn't penetrate saltwater very deep at all. It's worse than red if my memory serves me. So corals really never got much in nature, why would they need it in our tanks? But that's not to say it's a bad thing in our tanks. I just have pretty serious doubts.

 

[dartier]

Actually they do get exposed to UVA in nature (315-400nm). It does penetrate, though not as well as blue, but far better than red.

Here is a chart showing the depth in meters that the wavelengths of light penetrate.

So 380nm (which is what Kessil includes in their lights), penetrates to about 150m (492ft).

There was a good article comparing the amount of photosynthesis in corals exposed to single frequencies of light, and UV light near the visible spectrum (just below 400nm) had the biggest effect. Unfortunately I can't seem to fine the article right now.

Dennis

 

[kenneth wolfe]

I have 6 402nm 10w over my 180, it adds pop to the tank in reality I need about 3 times that to see while the whites are on but it looks great with the dusk to dawn..

 

[eb2292]

I can't speak on health benefits to the corals, but my AI Hydras have UV LEDs. I do find it adds pop to the corals during the ramp up/down times when the moonlights are on.

 

[dartier]

I found the article that I was thinking of.

Here it is: http://www.advancedaquarist.com/2014/5/aafeature

From the article above, this chart shows the rate of photosynthesis of corals illuminated with a various LED spectrums.

Other than Red, UV has the most effect of the rate of photosynthesis, and Red is not a colour of light that a coral would normally be exposed to (unless a very shallow variety).

Dennis

 

[Ron Reefman]

First, I can't see the chart you tried to present in post #4, please try it again and give a link to it, please. I'd really like to see it. But it didn't come from the Dana Riddle article that you gave a link to in post #7.

I did find this chart some time ago and it was the reason I said UV does not penetrate water very well at all.





So I'll admit that I'm confused. I found this article by Dana Riddle as well, and it draws a very different picture. Look at the scale at the bottom of the graphs and you see he is talking about profound fall off of UV penetration in just 15 inches! And then there is his final conclusion (highlighted in blue).

Ultraviolet Radiation and Aquarium Lighting
By Dana Riddle

...As can be seen, UV energy falls off rather rapidly.




We have seen that UV radiation has the potential to damage corals and other coral reef inhabitants. Many reef animals can produce natural sunscreens (MAA's) to protect themselves against UV but MAA concentrations are possibly a response to the amount of UV to which they are subjected. This is an important point since UV production among all tested lamps was not consistent and can change dramatically during normal operation or when the lamp is changed.

Our experiences suggest that coral coloration is a response to PAR levels, not UV. In short, we find no reason to subject reef aquaria to high UV levels.

Here is a link to the article http://www.aquarium-design.com/reef/uvlighting.html

 

[dartier]

First, I can't see the chart you tried to present in post #4, please try it again and give a link to it, please. I'd really like to see it. But it didn't come from the Dana Riddle article that you gave a link to in post #7.

Actually it came from another AA article but they seem to have blocked the link.

Second chart from the top showing a study by the Institute for Environment and Sustainability of the European Commission http://www.advancedaquarist.com/2012/10/aafeature

The authors of the AA article conclude that ~ 370nm to 500nm penetrate to a significant depth. 370nm to 400nm falling within the UVA spectrum.

To your point about the possibility that corals produce MMA's in response to being subjected to UV light, I feel that this may be why some people find that T5's and MH produce more colourful corals. Let's face it, corals in the ocean look nothing like the specimens we keep in our tanks. Most corals that I see while snorkeling are a variation of brown.

So if UV does play a part in bringing out these colours, then adding a small amount of it to an LED fixture may help to level the playing field with traditional lighting types.

Dennis

 

[twreefer]

I got a new AI Hydra, but will be awhile before I can mount it. So while it is sditting idle, would it add any benefit running just the UV at full strength over my sump?

 

[dartier]

I got a new AI Hydra, but will be awhile before I can mount it. So while it is sditting idle, would it add any benefit running just the UV at full strength over my sump?

That depends on what the desired effect is? If you are wanting to use it as a form UV sterilizer, then the answer would be no.

The UV sterilizers use a much lower band of light than the UV in your LED. The light from those units is harmful to all forms of life and why they have to be completely shielded.

If on the other hand you are trying to use it over frags in your sump, I would not run the UV very high as it is very bright to coral (but not to our eyes).

Dennis

 

[dkeller_nc]

One thing worth remembering is that while wavelengths from 360 - 400 nm may be fairly strongly absorbed by ocean water (though not as strongly absorbed as red wavelengths), the tropical sun is incredibly intense compared to our fixtures, and the total amount of radiometric intensity between 360-400nm may very high indeed in shallow (less than 30') coral reefs.

And it's precisely this spectrum (360-400nm) that is abundant in MH and actinic fluorescent fixtures that are almost totally absent in most (even high end) LED fixtures.

 

[Ron Reefman]

Please explain what you mean when you say, "...the tropical sun is incredibly intense compared to our fixtures..."

How are you measuring "intensity"?

 

[clsanchez77]

I got a new AI Hydra, but will be awhile before I can mount it. So while it is sditting idle, would it add any benefit running just the UV at full strength over my sump?

What are you growing in your sump? If algae, you would be better off with the whites and the reds.

 

[clsanchez77]

I have four AI Hydra 26's for my new 110 (not setup yet). These units do not have any light sub 400nm. I am looking at providing some additional HO lighting to supplement in this area as well as the cyan range.

The Kessil's do seem to have some sub 400 nm spectrum and I did not catch this difference when shopping around.

I am not aware of any DIY LED bulb that provides a sub-400 nm spectrum.

And yes, the sun is incredibly intense compared to any fixture we can provide. But that is not really an apples to apples comparison. What it really comes down to is the PAR/PUR levels we provide the corals in our tank (several inches of water depth) vs. what they receive in the wild (several meters of water depth). Available Lux at the surface is immaterial. Matching the exact spectrum is as much art as it is science and quite frankly, would produce a bunch of brown corals.

 

[jayball]

So for those of you guys who utilize LED systems that incorporate UV technology/lights, what are your thoughts? Is there noticeable difference/benefits that you associate with the presence of this type of spectrum?

Also.. does purple light in T5 lighting contain UV spectrum/wave lengths? I a bit confused as to what consist or is categorized as UV lighting. Does this only exist in LEDs or can this be achieved with halides and T5.

I'm running 8 bulb T5 ATI unit. Just ordered 2 all blue XHO Reef Brites. Thinking about adding an additional UV LED bar from Build my LED. What are your thoughts?

I suppose it depends on the size and depth of your tank but if you already have the reefbrites you can just add a couple 420nm actinic bulbs to your combo, you should have the power to spare. I would not add a 405nm only bar. A better option would have been to order the BML actinic or a custom layout with some 420nm added.