Led Lighting For 175Gal.

[ufoman420]

Im going to make a led light for my 175 gal tank. Im just trying to see if anyone has some technical data that could help me. The light is going to be 48"L X 12"W X 4" tall. I am just trying to find out how many leds are necessary to give adequate light to my corals and everything. This is what i can do, I can go with 36 180lumens white leds and 36 royal blue leds on dimmers which would give me 6480 lumens of white light. Or I can go with 20 540 lumens for double the price but that will give me 10800 lumens. Im just not quite sure how many lumens im gonna need to light this tank and grow corals. If anyone could help that would be awesome. I am going to drive them at 750ma or i could even step up to 1000ma for more lumen output. They are the Luxeon Rebel Stars if that info is needed. Thank you.

[kcress]

A noob huh? LOL

Check out these currently active threads:
http://www.reefcentral.com/forums/showthread.php?t=1672708
http://www.reefcentral.com/forums/showthread.php?t=1662682
http://www.reefcentral.com/forums/showthread.php?t=1678127

And welcome to RC.

[der_wille_zur_macht]

Can you give us some model numbers for the Luxeons you're talking about? Based on the lumen numbers, I'm wondering if you're talking about stars with multiple emitters mounted on them?

[ufoman420]

7007-PWC-10-3 it is the star with 3 led mounted to the board. the others are the same but only 1 led. I dont know if you can have too much light and i dont want to overspend so just doing some homework.

[ufoman420]

or should I go with the cree leds. They are 100 lumens min at 350ma

[der_wille_zur_macht]

Rebels vs XR-E is pretty much a wash if you're looking at the highest bins of both. The only real difference of course is that you can get stars with multiple Rebels on each, vs. the XR-E which are all 1-up.

I've used the 3-up Rebels in a few nano builds, and they worked fine for that. In a larger build, I'd be hesitant, unless you were going for really high density. They tend to contribute to the whole "columns of light" effect, since you're putting three emitters within a square inch. Compare that to using 1-up LEDs, where you'd have three emitters spread over 10 or 20 square inches.

Using 1-up stars is more soldering and mounting work, and probably a hair more expensive, but IMHO it is preferable since it gives you more even coverage, assuming that's what you're looking for. If you were trying to build a spotlight, or highlight a certain area of the tank, then the 3-ups would be great. But it sounds like you want even coverage, so I would suggest the 1-up LEDs.

What are the dimensions of the tank itself? What types of corals do you want? Keep in mind that coverage and spread is just as important as total lumens, especially considering differences in tank shape.

[ufoman420]

Cool that helps, The tank is 5ft long by 24" deep and 25" tall.say I went with the cree light How many would i have to have so i dont under light the system. I have hard corals, soft corals so pretty much all of it i want;). Right now i have 2 24" metal halide fixtures with 4 Actinic 65watt compaqs in each. The bulbs are about shot so 300 for bulbs or 500 for led? I think ill try Led

[der_wille_zur_macht]

It's probably gonna be more than $500 for a system big enough for your tank, though you'll make up the difference in a year or two of cheaper electricity and lamp replacement.

There really aren't enough builds for there to be a quick and easy answer, but most people are in the realm of 10 - 15 square inches of surface area per LED for the depth you have. You have 1,440 square inches of surface area, which means 100 - 150 LEDs, roughly. Most people are spending ~$8 per LED for a large fixture (this is a REALLY rough figure, and assumes you're doing things on the cheap) so you're looking at $800 - $1,200 in upfront cost.

[ufoman420]

Would that be White and Blue mixed Led's or just white.

[ufoman420]

because a guy that did a led build on this site used 24 white and 24 blue cree led on his 75 gal tank and his par ratings were good in diff sections of the tank well i guess i have double a 75 gal so yeah 100-150 would be right cool well thanks that will help out.

[der_wille_zur_macht]

White and blue mixed at those counts. So, maybe 40 blues and 60 whites, or however you want to break it up as long as it's around 50:50.

[Canoe]

... 3-up Rebels ... tend to contribute to the whole "columns of light" effect, since you're putting three emitters within a square inch. Compare that to using 1-up LEDs, where you'd have three emitters spread over 10 or 20 square inches.

Using 1-up stars ... gives you more even coverage, assuming that's what you're looking for. If you were trying to build a spotlight, or highlight a certain area of the tank, then the 3-ups would be great. ...


Interesting if one is trying to match the specularity of the sun-in-sky effect, which has ambient blue light from the sky and direct sun light.

Blue or Royal-Blue single LEDs, no concentrating lenses (possibly diffusion lenses?) could be used to provide the blue-sky light portion evenly throughout the tank.

3-up Rebel whites could provide the sun light. With the right diffusing lens, 3-up Rebel whites' light could be spread to provide coverage - same or similar number of LEDs & light intensity as using single LED fixtures, but the white "sun-light" coming from fewer points for greater specularity (light/shadow details & ripple within tank). This is trying to mimic how a MH filament in a reflector mimics the sun and gives a tank great detail & ripple, only we have a light zone for each white LED fixture, instead of a zone for each MH bulb.

This is all speculation, as, with the huge distance from the earth to the sun, it may be that many narrow focused white LEDs spread out evenly such that they have minimal overlap within the tank is the best mimic of the sun.

Darn. The only way I'll know is to build both and see...

[der_wille_zur_macht]

Darn. The only way I'll know is to build both and see...

Right there with ya. :D

My results so far indicate that it's really easy to get light too linear, and not diffuse enough. Natural reefs have a lot more space, and a lot more light bouncing around. In contrast, if you put a large number of LEDs very close together, especially with optics, the light becomes so directional that corals respond poorly (die-off on lower branches, etc.)

So, IMHO, you've either got to allow for some diffusion, or provide a means to move the LED array and change it's angle throughout the day (I'm gonna try both :) ) IMHO the ultimate would be close to what you're describing - lots of blue LEDs with diffusing (or no) optics spaced evenly over the tank. Fade them up and down on a curve following the intensity of daylight to provide a gentle backdrop. Then, bunch a ton of white LEDs close together, angled to they illuminate the whole tank, and tilt/move them over the tank as the day passes, also fading up and down as appropriate.