how much light

[jon1985]

I am in the process of building a tank for a haddoni. The foot print will be roughly 30" long, 24" deep and 20" tall. There will be a 3-4" sandbed so the light will only need to penetrate to 16" or so.

I was thinking about using LEDs.

Anyone out there keeping haddonis under LEDs? If so how much wattage do you have?

Thanks

[jon1985]

looking at 36 3w LEDs.

[Toddrtrex]

Wish I could help, but I have no experience with LEDs -- besides moonlights.

[jon1985]

its hard to say. I have found lots of cheap LEDs and some more expensive ones. Im tempted to try the cheaper ones because it would be about 1/2 the price but there has to be a reason they are cheap.

Obviously the tank will sit for awhile before the anemone goes in but I may have to try a few corals to see what they do under the LED. I hate losing anything but a $300+ blue carpet even more.

[bradleym]

Check the lumens output by the LEDs. White ones on ebay can range from 120 to 200 lumens and the only difference is price.

[jon1985]

the ones I am looking at are between 130-150 lumins. What Im not sure about is how many lumins/watts do I need?

[bradleym]

I am assuming that's 130-150 lumens per 3-watt LED?

Well, the average MH puts out around 80-90 lumens per watt. So a 150w = 13500 at best. Given that, 13500/150(lumens per LED) puts you right at 90 3-watt LEDs.

However, MHs put light out in all directions, losing alot to the back side of the bulb and out the sides of the tank, while a LED only does half that(being flat on one side). So you could probably go for about half as many, say 45 LEDs, to equal a 150 watt MH.

I've never done it myself, but I've been reading up on them for a similar future build and that's what I have gleaned so far. Before taking my advice as law though, I would suggest heading over to the DIY forum and reading other builds for several hours.

[bradleym]

Also, you can seriously improve the usefulness of each led by putting a 60 or 90 degree lens on each one. VERY highly recommended. :thumbsup:

They also make 30 and 45 degree ones but then you're getting pretty close to a spotlight/pinpoint in a shallow tank. Maybe if you hang the fixture a 3+ feet over the sand they would be ideal...

[jon1985]

yes Im looking at 60* lenses.

[BonsaiNut]

There is a lot of information about LED lighting on the lighting forum. LED's are a little more difficult to understand than traditional fluorescents or incandescents because of their narrow spectrum. They may generate plenty of PAR (photosynthetically available radiation) for your creatures, while generating less light that is visible to the human eye, so that they may appear dimmer while actually being better for your creatures. Additionally, because of the fact that they are a single point source, the question of spreading and shadowing comes into play. They are more like spotlights than floods, and you have to use arrays that overlap to create a curtain of light to cover your tank.

[bradleym]

Keep us posted! I am very interested in seeing a build like that for a haddoni.