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I've been messing around with the concept of using LEDs to provide the "dawn" and "dusk" for my tank. Another fun application could be to use a couple of blue shifted LEDs to simulate a little bit of moonlight or to use LEDs within the enclosure to highlight a water feature, plant, etc. with the overhead lights off. Also, given the relative pain involved in getting UV to plants, frogs, etc., I have thought about trying to find a UV LED and drilling through regular acrylic and flush mounting the UV LEDs so that there isn't anything between them and the enclosure. I don't think heat would be an issue and can only foresee a problem with eye damage if the frogs hung upside down very close to the source. If this is likely then there might be a way to offset the LEDs. Also, I think a UV LED probably will probably outlast the 1 year UV lifespan of your average tube or CF.

The problem is that would probably take some good calculations to figure out what the right intensity is, and some information about which wavelenghts of what UV are the ones necessary since UV LEDs emit UV in a much narrower band. The construct the LED assembly would also require some tweaking to ensure that the intensities were at the right level. Has anybody thought about doing this?

Marcos
 

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Yep, this is quite a common (well not so common, but much more so than vivs) thing used in aquarium setups. I ordered 10 blue LED's (420nm, which is wavelength of moonlight) from EBAY for like $5 or so. You will need to get some resistors and a adapter, but it's pretty general wiring although i haven't set it up for my aquarium yet.

Check this out though:
http://www.twoengineers.com/Richard/leds.html

Have fun and keep us updated.

Luke
 
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Don't waste your time searching for UVB leds. You will drive yourself crazy! 420nm is actually outside the UV spectrum on light tables. The basic bands are:

UVA 400 nm - 320 nm
UVB 320 nm - 290 nm
UVC 290 nm - 100 nm

UVB is what people and animals need to produce Vit. D. The rest of the spectrum can do some interesting things to organisms, but nothing you want going on in a viv :) UVA in small doses is cool, and is usually a majority byproduct of UVB illumination (IE: CF lights meant to throw UVB, actually throw 9% UVB and 91% UVA). There are some physics geeks who can get their hands on medium wave (320nm-290nm) leds, but nothing is commercially available yet. Once they become available, I will make sure to let everyone know!
 

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actually moonilight is just reflected sunshine so it is not a specific nm. The reflection factor of the moon is twice as much for the red as for the violet; thus it has a lower color temperature at about 4,125K.....when our eyes percieve light at lower levels it looks bluer than it actually is....the most accurate moonlight LEDs are usually the ones sold as "white"....
 

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Discussion Starter #5
Good to know. Look forward to seeing some of those scientific UVB LEDs make their way to market someday.

Regarding simulating moonlight, I have seen 420nm referenced quite a bit, and I think with good reason. While the moon is in fact reflecting sunlight as mentioned, the difference in intensity allows the rods to play a more dominant role in night vision. From what I understand, the peak sensitivity of rods is around 500nm and its the rods' production of rhodopsin that allows us to have night vision. There are certain lighting intensities (daytime conditions) that inhibit rhodopsin production which is a major reason why it takes a while for your eyes to adjust to the darkness.

For these reasons, I think the 420nm would probably give a better representation of nightime by simulating night vision (scotopic vision) or twilight vision (mesopic vision) under day vision conditions (photopic vision) rather than dim white LEDs. There is also something about those wavelenghts that allow them to land more on the fovea and create less eyestrain at night. That is supposedly (don't have a reference) the reason military aircraft moved from red lights to blue/green lights, NVGs are blue/green (except for the newer yellow tinted ones) and most of your car dashboards are a variation on this theme.

I was a Blackhawk pilot in my prior life and we had to learn all sorts of stuff about night vision. I'm a little rusty so don't quote me :)

Here are some good sites:
http://www.narcap.org/TheEyeandNightVision.htm
http://www.syz.com/rasc/lp/lightandtheeye.html
http://www.chemsoc.org/exemplarchem/ent ... dopsin.htm

Marcos
 

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i guess it comes down to the question of "who" you are adding the moonlight for....viewing pleasure or accurate simulation.....and no, neither reason is less justified...beauty of the hobby is selfish enjoyment :) oh that was great info by the way....ben
 

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hicksonj said:
There are some physics geeks who can get their hands on medium wave (320nm-290nm) leds . . . .
Yeah . . . when I looked into them 6-8 months ago, it was more than just physics geeks--it looked like you had to work at Sandia Labs. Brush up your government clearance levels and get your PhD if you want to get some of those! Joe, have some of those actually trickled into the research areas where typical University folks can get them? I'll bet they are uber expensive, even then!
 
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Homer,

The way that led technology is developing, I give it 6 more months to a year before medium wave leds are available for retail purchase. Most people don't realize the white leds are a recent invention, and since then they have been able to create ones that pump out over 100 lumens a piece :shock:

~Joe
 

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I agree that solid state lighting has come to market relatively quickly, but I know they were being discussed as much as 10+ years ago. I would not have thought UVB LED's would be available on the market as soon as 6 months, but I noticed that the UVC LED's went from scientific papers to production pretty quickly. I'm pleasantly surprised to hear production should occur pretty soon, as I was so angry that I could only find UVC LED's when I was looking. :x Sure, if you want to cook your frog or kill your eggs, UVC is fine, but who wants to do that?
 

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I have heard LEDs are far more efficient than halides, but perhaps that is a rumor? I have seen a few grow bulbs lit by LEDs, supposedly they enhance growth better as they only emit blue and red wavelengths.

Here's an old article about LEDs for night time viewing for a fish tank
For big tanks, I think it'd be more practical to use a 13 or 9 watt actinic blue cf.

http://www.csd.net/~cgadd/aqua/art_nightlight.htm
 
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