LED as main light

[AndyL]

Originally posted by micaheli
Hello, its me again (Ivo using Micah's account)

In the end I am still skeptical. Although I would love to see a
thriving reef (or plant...) tank under a low-cost LED fixture.

-Ivo

Ivo : you should get your own account...

I posted this earlier - it's a 4g nano with 6 1w luxeon star /o emitters. With thriving corals (albeit low-light). Hard to look at - imho but that's more because of the choice of blue LEDs (450nm) rather than the lighting itself.

http://www.nano-reef.com/forums/show...threadid=15832

Total cost for that system, is probably around 100$ absolutc could probably tell you exactly what it costs as he built/sold it...

Andy

[bluetropic]

I have not posted on this thread for a while but I found some thing interesting at Canadian Tire. I went to buy a tailight bulb for the old Chev. I bought LED replacements. They were like $12 CDN. They have different colours and styles. I thought they were handy because they were clusters of LEDs already wired together, resistors and all. Obviously all they need is 12v. Takes a lot of the guess work out. You could buy what ever kind of sockets you want. May at least be handy for making moon lights. The red ones would be good for night time veiwing. Also the "stop turn" LEDs had a big LED in the center, surrounded by regular ones. That could be handy for dusk/noon type setups. Just thought i'de throw it in.

[micaheli]

Yeah, these are probably not the intensity required to be used as lighting, but maybe a moonlight for sure. Good idea. Then somebody could use a PC power supply for voltage. More than enough wattage in one of those and they make them in small sizes for mini-atx and mini-itx form factors.

--Micah

[Obi-dad]

From a post above - '65-80lumen output (3w emmitter)). '

80 lumens / 3 Watts = 27 lumens per watt. If that quote is accurate, this is way lower than other light sources. If that is so, they may work fine for FO, lower-light corals, or freshwater, but are not quite ready for reef tanks.

[bluetropic]

My brother works at a sign factory. There they have a LED "strip", not a bunch of LEDs together, more like tape. It is not that weak stuff you see used as pin stripe, but something totally different. I am trying to get me some so I can check it out. Sounds pretty cool. Again, it may only be good for moonlighting. He says it is actually LED, so it should have lots of output, because the surface area. Rather then having a 0.25mm dot magnified, you have the whole width and length emmiting light. This could be revolutionary. I will keep you guys posted.

[Obi-dad]

That sounds like 'electro-luminescent strips (or panels)'. I used to work as a test tech for electrical engineers and we used those for lighting projects destined for aircraft like F16's and C17's (not sure if they ever made it into production). These are way cool for use in apps like those and are plenty bright to the eye (dimmable, low-power, etc), but I think not bright enough for reef tanks.

This post and others I have made on this thread may sound negative to some, but I am only playing 'devil's advocate' -- I would love for someone to develop alternative light sources for reef aquariums (let me know if I can help develop, I have a little background in electrical engineering and plenty of experience in computer programming).

[sandisct]

"The guy told me that the maker of these LEDs have a replacement for 1000W MH flood lights that use 10 of these LEDs (I **** you not, thats what he told me) They cost $50 AU each though.

I think that comparing wattages is 100% irrelevant when dealing with LEDs. LEDs can automatically shine straight down at 15 deg, so much more of the light they produce ends up on your coral instead of being absorbed by your lighting hood and the walls and carpet of your house. This must be considered when comparing LEDs to other forms of lighting."

I'm not sure whether the lm/w thing really works for LEDs. .... any documentation on it?

[DennisRB]

I have no documentation on it. I am skeptical about what the guy told me.

[bzzbee2]

humm.. all sounds cool...

anyway i just found out some interesting news for all us californians... go to the PG&E (pacific gas and electric) website and look at their tool library. they have a vast array of light meters, which are free to check out and use, all you pay is the shipping. you may have to wait a few weeks or maybe get in a que to get a specific light meter... but its worth it if you can get your hands on a waterproof meter...... we could auctually get some good readings from the depths of the tank...

hint hint.

i will be checkin this out when i get to work tomorow.

[olemos]

Originally posted by sandisct
"The guy told me that the maker of these LEDs have a replacement for 1000W MH flood lights that use 10 of these LEDs (I **** you not, thats what he told me) They cost $50 AU each though.

I think that comparing wattages is 100% irrelevant when dealing with LEDs. LEDs can automatically shine straight down at 15 deg, so much more of the light they produce ends up on your coral instead of being absorbed by your lighting hood and the walls and carpet of your house. This must be considered when comparing LEDs to other forms of lighting."

I'm not sure whether the lm/w thing really works for LEDs. .... any documentation on it?

let me understand this He has a bulb made with LEDs that will replace a 1000 w metal halide ?

[DennisRB]

Thats what he told me anyway.

[micaheli]

Well find out! I'd like to learn more about this replacement! Sounds pretty spectacular to me.

[DennisRB]

It sounded more like a hand down story to me than anything else. I don't think the supposed unit has reached production. Next time I go to that shop I will ask more about it.

[micaheli]

Indeed. Sounds like a whopper actually. But, if he has one... I want one. So yeah, find out more next time you are able to ask.

[MadTownMax]

FWIW:

How do you convert lumens to mcd ?
There is not an exact conversion since they are different types of measurements but here is a rough conversion:
If you divide the number of lumens by 12.57 you can get the equivalent candelas, candelas X 1000 = mcd

HTH

[bzzbee2]

well, i have read this entire thread and i think it was mentioned, but here it is again. "Pulse width Modulation" does anyone know where you can get one of these modulators? by using one of these you can pump 100mA through a LED verses only 20mA. it does this by pulsing the energy through the LED at a certain frequency such as 10x per second. you dont get a flashing effect from what i have heard. but you can drastically increase the brightness of a LED. so if bumping the amperage from 20 to 30 gives you a 30% increase in light. imagine what going from 20 to 100 mA would do? I am not exactly sure about all this but i have read it in several other areas, and was wondering if anyone had experienced it yet?

as for my white led's. I wired up three and auctually doubled the resistance... after 2 minutes, i noticed that the blue hue that was shining on the wall was starting to get some yellow tint to it.. then it just shut off and i smelt that awesome burnt LED smell... they were wired in series. the first one fried. the other two were dead, but were not black in the middle.... i rewired parallel, and all is well. after mounting them over the tank that blue hue from the super bright led was filtered out and only a more yellow light was reaching the bottom. but when shined on high areas in the tank it looked alright. 10,000mcd just isnt enough. i think we need like 100,000mcd.... hehe I am serious about trying this pulse width modulation thing, so if anyone knows where i can get one let me know.

[polymorphus]

this might be an intresting read for most:
http://www.nano-reef.com/forums/show...D&pagenumber=3

[MadTownMax]

Polymorphus - thanks for the link, that really helped me understand the DIY aspect (and $$$ associated) of this type of a project.

anyone up to date on what the best wavelength is for growing plants? I've seen that clorophyl is supposed to absorb two wavelengths from 650-680nm and 680-700nm, which I hope the white LED's cover fairly well, but I think that I might order some red or orange (these colors offer some mcd's around 10,000 and have peaks in the 650-700 nm) LEDs to really get the macro going.

Any helpful comments would be appreciated.

[AndyL]

Growing plants is pretty easy - the plants do require some blue light (tells them in which direction to grow) I believe its 430nm then I believe its 630nm and 670nm for actual photosynthesis. White LEDs are quite capable of producing these ranges - if you look a few pages back I posted a measured spectrum output of a white LED - tho that may not be representative of all leds output... But the one's I've tried have shown good results (better than the PC lighting they replaced)

Andy

[MadTownMax]

AndyL - excellent, that helps as the red spectrum chart shows even more relative intensity at those lower wavelengths, I'm going to use white anyway, but if I'm not seeing satisfactory growth from my macro (especially want to see how this affects gracilaria) I'll add some reds/orange/yellow LED's to the mix.

-Nick

[AndyL]

http://aquabotanicwetthumb.infopop.c...2&m=1156008725 is definitely worth a look - There's some tech data there specific to aquatic plants (albeit freshwater).

Andy

[sfsuphysics]

Originally posted by bzzbee2
well, i have read this entire thread and i think it was mentioned, but here it is again. "Pulse width Modulation" does anyone know where you can get one of these modulators? by using one of these you can pump 100mA through a LED verses only 20mA. it does this by pulsing the energy through the LED at a certain frequency such as 10x per second. you dont get a flashing effect from what i have heard. but you can drastically increase the brightness of a LED.

Well I can tell you if it flashes at 10 hz you would definately see it flash. Anyone remember headaches that occur from 60hz fluorescent flicker??

Anyways yah, its what police guns use for their laser sight, they found that if they pulsed their laser they get a longer battery life out of the laser. Dont really know how effective it'd be on a tank though *shrug*. What you could do if you're handy with electronics build a rectifier bridge that'd clip off the negative downswing of AC current so your LEDs should work, although that'd be limited to 60hz which would still be quite noticable as a flicker.

[robwsup]

You could use a capacitor to phase-shift the incoming 60Hz, and run a seperate bank of LED's. That would reduce the perceived flicker.

[bzzbee2]

oh.. i forgot to throw in the k... kHz. i wasnt reading my supporting info correctly.. so where i thought was 10x it should have been much more i have found a few PWM's that will pulse upt to like 5 KHz, and down to 100Hz. wether or not this method will work is another story... and when i figure it out i will let ya all know..

[sandisct]

seems like the luxeon ii really work