There are many threads out there of people experimenting with LEDs, some making lamps using a few powerful 1W or 3W LEDs, others using many lower powered 5mm LEDs, most of them experimental. Here are some that inspired me:
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1587273
http://reefcorner.org/forum/luminaria_led-105761
After checking possible LED sources, I found a supplier at Mercado Livre selling 5mm LEDs of 20cd with lens and resistor at a reasonably good price. Twenty candelas is very little, but I figured out that a lamp made out of 20 LEDs in a fairly compact configuration, totaling something close to 400cd, could probably substitute my Coralife 50/50s. My idea was to make a 50/50 lamp too, with 10 white LEDs and 10 blue LEDs. Unfortunately I made a mistake and ordered 20 blue LEDs, so the first prototype was completely blue. The cost would be R$75 per lamp (~US$42) considering the LEDs and a plastic box to serve as lamp case, still expensive but less than the R$120 and with the potential to last 5 to 10 times longer...
I didn't know I was in for a very nice surprise.
Enough talking, let's see some pictures.... here are the LEDs and lens the way they arrived from the supplier
Here is the plastic case after drilling. I made the 20 holes in a 5x4 rectangular grid, with 20mm horizontal spacing (row of 5) and 15mm vertical spacing (row of 4). The plasticbox didn't permit 20mm x 20mm.
Here are the LEDs installed in the box:
Here is half the lamp lit up (I wired it as if it were half white, half blue):
Here is a picture of my aquarium hood removed and upside down, and another of the tank without the hood:
Here is a picture of the light installed in the aquarium:
Now, what a surprise when during initial tests I pointed the lamp towards the corals.... incredible fluorescent colors.... the hammer's green tips lit up beautifully, the green star polyps' grass-like arms lit up, the acan had a bright orange color, the zoas' tips lit up orange and green, and the palithoa's green middle also lit up beautifully. The pictures below give you just a very rough idea... the real thing looks muuuuch better/brighter (and isn't blurred :-) ):
I ordered 20 more white LEDs, and 6 red LEDs to see what their effect would be (thinking about a 21 or 22 LED lamp setup with 10 whites, 10 blues, and 1 or 2 reds in the middle). Why red? Because scuba diving lights are normally reddish.
One day before I built this LED lamp (27/Jan) the fifth Coralife burned.... my plan is not to swap everything for LED lamps right away, but rather build new ones as the Coralife lamps burn or reach end of life. Kind of like a more cost effective lamp change, with the benefit of higher light quality.
And these LEDs lamps won't only cost less and look better, they also won't burn with inconsistent voltage because their power source will take care of providing a stable 5V DC to them, and they'll last a lot longer than a fluorescent lamp. :-)
