# LED fish tank light project



## joraff (Feb 15, 2007)

I'm interested in trying to build a light for a 55 gallon fish tank from LEDs from various bin p3's and/or p4's (various bins to create a wider spectrum).

_My largest concern is how to disperse the light so that there aren't many hot spots_ and I could use some input from these forums to build an idea. My current idea is to mount the LEDs at the ends of the light fixture and create some kind of "light bar" similar to a fluorescent, such as an opaque polycarbonate rod.

I'm really new to light modding, and don't know much about LEDs but I thought I could learn best by doing. Thanks to all who contribute


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## 2xTrinity (Feb 15, 2007)

Is there any particular reason you want to go with LEDs as opposed to a fluorescent light (there are even fluorescent lights with phosphors optimized for aquarium use)? The fact that fluroescent is naturally diffused is one of their biggest advantages compared to LEDs. Not that there's anything wrong with using LEDs -- that should work okay, but it could end up being a lot more expensive to do it that way.


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## joraff (Feb 16, 2007)

No, no particular reason. In fact I have fluorescents working just fine on the tank right now. I am really interested in modding lights and these LEDs, but don't personally have much interest in flashlights, which seem to be the most common thing built around here.

I'll probably do a mag mod to get a feel for any LEDs that I use. 

I'm curious to see how possible it is to diffuse a point source of light, in this case over the water surface. 3M makes a product called Light Fiber that supposedly distributes a point source of light over its length (with a loss of ~3%/meter) making it appears much like a neon tube or fluorescent tube. I am curious to see the effective luminosity from the light tube with an XR-E at each end in comparison with a fluorescent. 

I'm not growing plants, breeding, or lighting a marine tank, which would all require specialized wavelengths. 

Has anyone had any experience with this Light Fiber?


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## 65535 (Feb 16, 2007)

You could use the LED's and use a wide angle optic such as the 75 degree ones made by cree, or others with an bolong shape that cover width rather than hieght.


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## Diesel_Bomber (Feb 16, 2007)

Just sand the epoxy coating the emitter.

:buddies:


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## 2xTrinity (Feb 16, 2007)

joraff said:


> No, no particular reason. In fact I have fluorescents working just fine on the tank right now. I am really interested in modding lights and these LEDs, but don't personally have much interest in flashlights, which seem to be the most common thing built around here.
> 
> I'll probably do a mag mod to get a feel for any LEDs that I use.
> 
> I'm curious to see how possible it is to diffuse a point source of light, in this case over the water surface. 3M makes a product called Light Fiber that supposedly distributes a point source of light over its length (with a loss of ~3%/meter) making it appears much like a neon tube or fluorescent tube. I am curious to see the effective luminosity from the light tube with an XR-E at each end in comparison with a fluorescent.


This is actually an interesting idea for an accessory to a flashlight -- an alternate cap with a diffusing tube that you could screw on "light saber" style in order to use a flashlight as a lantern. You could also make a better alternative to those bulky CFL lanterns -- with the batteries and a couple LEDs _inside_ a light tube, like one of those chemical glow sticks but a lot better.



> I'm not growing plants, breeding, or lighting a marine tank, which would all require specialized wavelengths.
> 
> Has anyone had any experience with this Light Fiber?


I haven't, but it sounds like it could be used for some pretty interesting effects.


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## Ken_McE (Feb 16, 2007)

_My largest concern is how to disperse the light so that there aren't many hot spots_ 

One thing that comes to mind is to use a larger number of small LEDs, perhaps a strip that runs the entire length of the tank with a row of smaller LEDs all the way along it.


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## 65535 (Feb 16, 2007)

I was thinking wide angle oval optics.


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## joraff (Feb 17, 2007)

The widest angle I could find, I will still need the emitters to be about a foot above the water level, which isn't an option. 

I've calculated the surface area of the water, and the aproximate height above the water of the emitters, and I'll need at least a 100º lens to be able to light the water surface to about 90% coverage with only 7 leds in two rows - one of 4 and one of 3.

As for the strips, I hardly know anything about other LEDs besides the xre and ssc p4. How many (I assume 5mm leds) would it take to get about 1000 lumens to the water surface, and how much do they cost/led?


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## bombelman (Feb 17, 2007)

My idea, heatsink these (Luxeons or Crees) on a copper strip.
Then use a diffused tube of translucent plastic or glass, similar to a 
flourescent tube. The tube will diffuse the "beam".

You can even mount colored emitters on that same strip,
insert a rotary-knob and you can add some color...
Or even use Red/Green/Blue instead of all white emitters...

Cheers !











RGB model:


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## joraff (Feb 17, 2007)

Yes, that's exactly what I was talking about w/ the 3M Light Fiber! 

Now, if I can only get a dang distributor of the stuff to email me back...

Anyone know of a different brand that would do the same thing?


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## liveforphysics (Feb 17, 2007)

Critical angle of reflection will result in all photons strikeing the surface of your tank at an angle greater than 44deg from perpendicular to reflect rather than penatrate.

This means you will require fairly focused optics to enable the light you create to become useful. I would definately not concern yourself with seeing a series of hotspots in the tank. The surface turbulance and distance to the bottom will definately prevent this from happening. I've tried a couple of LED arrays for aquarium useage a few years ago. For my application which is purely to grow coral, the lack of high power 415nm-430nm LEDs caused the arrays I made with hundreds of the brightest white LEDs I could find to be useless. As far as lighting purely for the purpose of viewing illumination, I did a little test for you with 4 different overdriven CREE flashlights aiming down from the top on 1 half of a 55gal tank in the dark. It was pretty weak and pale, with terrible looking colors on the corals and a sickly unhealthy appearence. Keep in mind that I am used to seeing this tank be hit with 30,000lumens of light in ideal wavelegnths to cause florecence for 11hrs a day, so I am going to be naturally a little funny about what I expect to see.

If I slid all 4 flashlights together and just tried to light the front corner area (about a 6"x6" patch), it appeared bright enough, but the colors just looked like something from the morgue rather than an aquarium. Also, if I lifted the lights just a few inches above the water the lighting pretty much dimmed to nothing in the tank.

A company called Solaris makes LED lighting for aquariums. They use something like 100 luxeon K2's for a typical 55gal tank setup. Draws around 300watts, makes lots of heat, the tank appears dim with poor coral colors and ZERO florecence. The corals all die within a short time due to no wavelegnths of light that support ClorA. The website for the Solaris product is an absolute hysterical sack of lies. 

http://www.solarisled.com 

If you want some excellent lighting for just viewing purposes, I highly recomend T5HO with proper reflectors. 1 bulb should be more than adquate for just viewing purposes. You will be looking at 54watts @ 95-110lumens/watt to get you ~5000lumens of light into your tank while taking up minimal canopy space and low heat. Bulb phosphors available in any flavor you like, and if you ever decide to step into a planted-tank (highly encouraged) or a reef enviroment, you will allready have a part of your lighting needs ready for the conversion.

Best Wishes,
-Luke


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