LED as main light

[Gomer]

just a correction...22 amps, but NOT at the same voltage

LEDs are around 3.5V in the white flavor.

...so more like 77 watts.

...not practical or realistic anytime soon on large tanks. ...but on nano tanks, it is very possible.

[Rikko]

Haha I knew I missed something; my first calculations weren't that out of range!

Well, my next little stupid project will be to make some LED pendants for my 65 to hang over SPS to give them a little boost.. We'll see how that turns out.

[Gomer]

I actually wanted to make an LED pendent, but need to get a driver for that much power first. I was looking at running a 5x5 grid of Star III emitters. All in due time I suppose

[Rikko]

My idea is to make a small funnel that is reflective and line it with LEDs and hang it right over the corals that need a little love.
Basically I took a CD and make a cut from the hole to the edge, then overlapped it a bit and glued it in place. Instant, cute reflector, right? Looked great and I think with many LEDs in it it would look pretty good and give off a good bit of focused light (assuming that you get the correct cone shape to focus the light at the depth you want)..
The only problem there is that the CD is under such pressure being glued there that it tears itself in half (at the glue point or somewhere else) after a few minutes.
I'm hoping to get my hands on some very thin mirror acrylic that I might be able to bend enough to get it to hold without essploding.

[chucklez]

I guess im sort of a dummy, and I probably should know this as I have been following this thread for a loooonnngggg time now, but why is it impractical for a large tank?

I mean, looking at Rikko calculations, a array of Leds occupying the same space as a T5 bulb puts out roughly 3 times the output of said bulb. Therefore, couldnt you space the LEDs out a little more to cover more area, thereby making the LEDs more energy efficient? Do you follow me here?

I guess the main question here actually is, How much wattage does it take to run a T5?

[bzzbee2]

part of the problem from what i understood is that they have such a narrow spectrum that they dont penatrate h2o very well.. at least that was my understanding... although if you could wire up 100 of those luxeons you may have something... but who wants to pay that much for lighting.

[chucklez]

Are you talking as in color spectrum, or in beam width?

[hydro]

HI
So I have to ask, are you guys that hard headed or am I missing something I found these lights. They are already prewired, 120v with a reflector all you have to do is mount a light socket and go.
led light
Or are you just waiting for me?
Joe

[bzzbee2]

i was refereing to color spectrum... however the tests with plants dont seem to show many problems.

joe.. how many fixtures can you fit over your tank.... for the price of one of those bulbs that contains 8 LEDs you can buy 100 LED's in order to get the lighting out of those bulbs that you would need... you would have to have a lot of them.. which would cost quite a bit of money, not to mention the amout of plugs you would need, unless you wired several sockets into one plug....
These would probably work great for a nano, or fuge...

However that Luxeon bulb fixture looks pretty dang interesting. What kind of fixure is MR-16? what do you need to plug in that luxeon bulb...

[bzzbee2]

ahhh.. found the fixtures... i would like to have like 4 of these with luxeons.. or maybe some of those led setups for my fuge....

http://www.ylighting.com/ylighting/linsysmod214.html

[Gomer]

Rikko: Scrap the whole reflector idea. the beauty of LEDs is that you don't need them.

Bzzbee2: The color spectrum is good. It is MUCH broader than normal fluorescent bulbs which are pretty much a combination of 3 sharp lines.

hydro: typical white LEDs do not have a very long color maintanence compared to Luxeons. There is lots of data out there that shows how quick the typical ultrabright white LEDS reach 70 and 50% levels.

Bzzbee: That single watt fixture may look interesting, but it is quite expensice..it also looks like it is underdriven. Also note that you still need a DC power supply for those. You can DIY it with a lot less in expensise. $30+shipping for their 1watter. Not including a heatsink, I recently put together a 3x3watt setup with 30°columating lense for about $40+shipping.

[bzzbee2]

True, the bueaty of one of those is how it would look in a nice fixture... you could get one of those fancy monorail type fixtures with 4-5 outlets on it... it would look nice. but your right it would be pricy...

[Rikko]

Originally posted by Gomer
Rikko: Scrap the whole reflector idea. the beauty of LEDs is that you don't need them.

Not entirely true. Since it's a directed light, we don't need to reflect around the side/base of the bulb because the light output there is basically negligible.
Reflection comes in handy when you have a lot of directed light going over the surface of the water and lots of it bouncing off the water surface never to be seen again (pun intended).
Like bzzbee said, they don't penetrate through water surface as well as other lighting technologies - so they light has to be going somewhere. With a reflective sheet right behind the LEDs, you can recoup your losses somewhat. I haven't made up a little rig yet to test that (got a lot of CDs around here.. I should try it over a small tank and see if it's noticeable to human eyes).

[jeremism30]

I know that NASA has done a lot of work in growing plants with LED's.

[Gomer]

Nasa did some work with discrete LEDs, not white ones...atleast not in any papers I have seen. White is for "our" eyes. You can get better growth by using descrete overlaping lines and not waste extra energy.

[chucklez]

So, lets summarize this thread since it seems to have died recently.

If someone could just fill in the answers, it would be great.

1.) Are LED's a practical source of main lighting for a reef tank?
a.) Large Reef?
b.) Nano Reef?

2.) What advantages/disadvantages (ie. initial setup cost vs. MH or VHO, electricity usage, heat issues) are there?

cant think of anymore. maybee over the weekend I will.

[robster]

I have three moon lights on my Current-USA PC fixture. They create a MH like shimmer on the bottom of the tank with just three. That tells me the penetration of light is intense like MH. I would be very interested in seeing some PAR readings myself. It would be nice if these could put out similar PAR as MH with lots of these LED's. No heat, low power consumption, never replace bulbs. Sounds good to me.

[Obi-dad]

Shimmer is caused by point-source lighting, it is not specifically an indicator of intensity.

LEDs DO produce some heat.

[chucklez]

Originally posted by Obi-dad
LEDs DO produce some heat.

Yes, but it is minimal compared against MH.

[Gomer]

LEDs produce lots more heat than people give them credit for. I think you need to play with some luxeons for a while to appreciate how hot they can get. I think we need a rich person to whip a a 150watt Luxeon array to compare to a 150watt MH

[dcoufal]

Luxeon's produce more heat than regular LED's because they're being over-driven... that's why their rated life is nowhere near the 100,000 hours of a regular LED.

Drive an array of regular 10,000mcd LEDs at their rated spec's and you will have little to no heat generated.

(I'm still playing with my 1000 LED array for my 125gal FW tank.)

[xrunner1234]

Originally posted by Gomer
LEDs produce lots more heat than people give them credit for. I think you need to play with some luxeons for a while to appreciate how hot they can get. I think we need a rich person to whip a a 150watt Luxeon array to compare to a 150watt MH

150W is 150W. The reason why MH is hotter to the touch is because it cannot be cooled as effectively as a bulb that has a larger surface area such as a few PC bulbs. The more heat you can remove from the bulb through convection, the cooler it feels and the less heat will transfer to you tank.

[Gomer]

Dcoufal...You might wat to look at this white paper with respect to lumen maintenence of 5mm LEDs.
http://www.lumileds.com/pdfs/protected/AB07.PDF

Xrunner. you need to consider inefficiency losses. an extreme example is a 70watt incandecent vs a 70watt HQI.

[xrunner1234]

Originally posted by Gomer

Xrunner. you need to consider inefficiency losses. an extreme example is a 70watt incandecent vs a 70watt HQI.

Can you elaborate? I am not talking about light output vs heat but rather power dissipated vs heat.

[Worldwithin]

For those of you that are still checking up on this thread, I finally have put together an LED array for my sump, soon to be fuge.

I decided to use a total of 90 LEDs for this array which makes it rather bright, 50 13000mcd white and 40 6000mcd blue LEDs.

I think that the power supply was the biggest issue as the total array uses 12vdc at close to 2+ amps. Finding an affordable power supply for this was interesting, luckily I managed to acquire one from work that is rated at 6 amps if I ever decide to add a second array to this one.

Unfortunately, I do not have any par or meter readings as I do not have a meter to do so with, but I will post updates as to see if anything ends up growing in my sump with this array installed.









http://reefcentral.com/gallery/data/...45P1010281.JPG