Seth's DIY Cree XM-L LED build

[Seth81]

Hello everyone, I've gotten a bunch of questions about my DIY light fixtures. So I thought I should make a new thread about it.
First off my goal is to have an automated dimmable lighting solution with a night mode that is capable of growing coral, with minimum Algae growth (so cool light all the way).
Basically I designed 5 Lighting strips suspended over my tank with aircraft cable hanging from my canopy rails. This way they are mobile and easily removable.

Here is the Basic LED layout:

Components
5 x 24"x4" Wide Heatsinks from Heatsinksusa.com
20 x Cree XM-L T6 Bin 1B cool White LED's mounted on Star PCB from www.cutter.com.au
15 x Cree XP-E Royal blue LED's mounted on Star PCB from www.cutter.com.au
35 x Star PCB shaped thermal pads from Cutter
2 x 100 Watt Thomas Research products LED dimmable driver (2.8 Amps) from www.thomasresearchproducts.com
1 x 40 Watt Thomas Research products LED dimmable driver (700 mA) from www.thomasresearchproducts.com
5 x 12 VDC Computer fans from Ebay
100' #18 AWG hook up cable from Active Electonics
5 x project enclosures from Active Electronics
5 x 8 Way Plastic terminal stripes from Active Electronics

Make sure you get some spare LED's I did have one of the whites burn out on me after 30 minutes.

Design Data
Here is just some numbers if anyone is interested:



I tried out the fixtures with no fans at all...and after a few hours they got too warm to hold, not burning hot or anything, but too much to be constantly touching, so I decided I needed the fans after all. With one fan per fixture the heat sinks stay room temperature.


Driver Specs:

According to the LED spec sheet, at 2.8Amps the forward voltage is 3.35 Vdc, so the voltage range is the limiting factor to the number of LED's I can connect per driver. The model below would be good for 8 - 12 white LED's at 2.8 Amps



The driver is dimmable via a 0 - 10 Vdc signal. I plan to connect this up to my PLC (programmable logic controller) and make a whole sunrise/sunset routine.

I decided against optics at this point . The LED's naturally have a very wide angle light distribution, almost too wide over 120 degrees. The only reason I may use optics is that my tank is 38" tall, and if I find that the light penetration isn't that good i.e. not enough light at the very bottom of the tank, then I will spend the $6/ fixture I was quoted. But when I turned the fixtures on I seriously doubt I'll have a problem.
I promise to add some more pictures soon...i.e when I am not at work

[BigAl07]

Very nice looking layout!

[Stones]

Looking good man, can't wait to see some pics of it up and running.

[Reefer Rob]

There is a massive LED aesthetics thread on RC you might want to read before you go with cool whites. Lots of people complaining the light is very flat, and they add reds and greens trying to improve the color.

I went with about 2:1 royal blue to neutral white and to color is gorgeous. After only 2 weeks it's still too early to say anything about algae growth, but I believe corals also need red spectrum.

[BigAl07]

Originally Posted by Reefer Rob

... I believe corals also need red spectrum.

Your shallow water coral are adapted to utilize some degree of reds for sure. Plus adding a titch of reds & greens is tend to be very eye pleasing to the Homo sapiens in the equation.

[Seth81]

Originally Posted by Reefer Rob

There is a massive LED aesthetics thread on RC you might want to read before you go with cool whites. Lots of people complaining the light is very flat, and they add reds and greens trying to improve the color.

I went with about 2:1 royal blue to neutral white and to color is gorgeous. After only 2 weeks it's still too early to say anything about algae growth, but I believe corals also need red spectrum.

Looking at the attached flux distribution for the XM-L's I would say there is no need for any additional green lighting. Red... well maybe, but that might encourage algae growth. I think I'll try out my setup for a while. The only mods I am considering right now is optics and some more royal blues for better actinic lighting and a cooler (K) look




Edit: Looking at the XP-E Cool Whites, there seems to be slightly more green content in the XM-L cool whites

[Reefer Rob]

Yes the optics are nice, they keep the light in the aquarium, not the room. I tried without first and found it had too much light spillage, but it did have a nice T5 lighting effect. With 80 degree optics there is way more shimmer and more of a halide look.

[BigAl07]

Originally Posted by Seth81

Looking at the attached flux distribution for the XM-L's I would say there is no need for any additional green lighting. Red... well maybe, but that might encourage algae growth. I think I'll try out my setup for a while. The only mods I am considering right now is optics and some more royal blues for better accentic lighting and a cooler (K) look

Yes the XM-L's do have a much wider "spectrum" than any of the other LED and are an excellent choice to get more Spectral Diversity in your fixture.

Are you going to run these off of a controller or just manual dimming?

[Seth81]

I'll be running these off of an industrial PLC (Programmable logic controller) using two seperate 0-10 Vdc outputs, 1 for white, another for blue.

Originally Posted by BigAl07

Yes the XM-L's do have a much wider "spectrum" than any of the other LED and are an excellent choice to get more Spectral Diversity in your fixture.

Are you going to run these off of a controller or just manual dimming?

[BigAl07]

Siemens?