UV LED over tank

[StirCrazy]

Originally Posted by sphelps

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.

yup you are correct, but the UV-A range is a generally harmless range and some of it is visible. (although it appears very very dim.) when people are talking about UV LEDs generally they are not talking about real UV LEDs as at 50 bucks a shot for a reasonable strength one they are not a cheep options. good ones are in the 120 buck range.

rather we are talking about "Near UV" or true violet as they are referred to, which have a peek about 417. the reason for including these is the royal blue LEDs peek around 450 nm and are very week around 400.

so in reality a true violet just is a common sense addition to any LED system to ensure complete coverage from 400nm up.

now people have been playing with the 365 to 400nm range and personally if I could find a affordable LED in that range I would add it also as that area does have some effects I enjoy also. This range is also included in any decent MH bulb.

Steve

[Jaws]

So how many true violets would you recommend then over a setup like mine, if any? So far I've gone with 164 RB, 54 White, 12 Red, and 12 Green.

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[Jaws]

Sorry. 144 RB and 72 White

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[sphelps]

Jaws I think if you're considering violet LEDs or whatever you want to call them then you should also consider Blue and even cyan. Personally I'd take the number you have in mind for RB and split it up. Consider an equal amount of violet, RB and blue and then probably half the amount of blue for cyan. for example with 144 RB leds, consider instead 48 violet, 48RB, 48 Blue and 24 cyan. This will also decrease the amount of white you need.

[Jaws]

Unfortunately I've already built the pendants with the configuration above so I have to look at tweaking what I already have.

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[ScubaSteve]

I think, like I said before, spacing them every foot would suffice. So go with a 2 x 6 grid... So 12.

[StirCrazy]

personaly, I am taking 1RB, 1TV to every 1Nw.

I think every foot is a little far for adding it in, but what you could do is srart out by adding 10-20 of them, then save up some more money and add another 10 to 20 of them.. ect untill you get close to the same amount as your white, or untill your happy with the results. maybe at 20 of them you will like the look and stop there.

what kind of whites did you go with? this also will determin how many you will end up with, might not ba able to use as many with cool white as with a different white.

Steve

[daplatapus]

I just finished my LED build yesterday and sat it over my cube last night. Today was the first real day I was able to see what it all looked like. On a 18" heat sink (and yes I know this is a bit overkill ) I have 6 Cree XTE 3W RB's (3 of these I'm using for moonlighting), 6 Exotic 3W True Violet 420nm, 6 Cree 3W RB XP-G NW 3up stars, 2 Exotic 3W OCW 3up stars.
All I can say is HOLY COW! True, I came from a couple of cfl's as temp lighting because this was an emergency put together tank but I decided to make it nice. The greens and red's explode off coral and fish. The greens glow. It (in my opinion) looks amazing!I have all the RB's on one driver, the OCW's and the TV on another and the NW on their own. Turning off the OCW/TV driver turns the tank back to fairly bland again. I am so glad I got these TV LED's.