LED lighting

[bdejong]

What I read on another forums,some moderators test these LEDs and their coral didn't open well under them.I know some coral may open alot when they are not given enough light,so I'm not certain that this was the case.Their final statements were that they felt that LEDs didn't penetrate the lowest part of their reeftanks like medal hallides and that it would take more LED bulbs then a standard size fixture to accomplish comparable results to medal halides.

Interesting, this is the kind of information that I am looking for. Here is what I think is going on. Most, if not all commercial white LED's target the standard household color temperatures. This is usually from 4500K to 6500K. this is what "people" want to see so that is where they are targeted. What is missing form all of the LED lamps I have looked at so far is additional BLUE (450nm) LEDs.

Advancement in the Lumens per watt output of a power LED is happening extremely fast right now. Consider the normal cycle for getting a product into production, the devices that they started with 6 to 9 months ago are now considered low output.

I would think that the main reason some of the early test lamps didnt do to well was from a combination of not enough light output and not enough light in the right wavelengths. What I am finding out is that the MH lamps that are popular are very heavy in the blue spectrum. The appearance of these lamps is noticeably blue. In some cases very blue. It would be unacceptable for most all LED applications to produce a "white" LED with such a high color temperature.

The next step for me is to do some comparisons in the lab of the typical output of a MH lamp and then test how many LED's it takes to produce the same amount of light. Take a look at the following link, it is a picture of the new light fixture used in the parking garage. this one fixture replaced a standard sodium lamp and puts out more light with less power.

Raleigh, N.C. to replace street lights with LEDs | Planetizen Radar

I curious to know how you incorporate the slow transition from dusk to dawn.In my mine,that would seem like a gazillion timers.Is their an alternative to the bulky outlet kind and the digital ones that can transition the amount of LEDs needed for a more realistic day cycle?

This is another area where using LED's is easy, its as simple as varying the duty cycle to the LED's. Powering the LED using a simple PWM controller is not that hard, and will enable the dimming of the output. What I dont know is at what point the LEDS color temperature starts to fluctuate. But I will find out.


EXCELLENT discussion, keep them coming. I have tried to post a picture twice now but the post is not showing up. I will try again here.



Brian

[bdejong]

For you who are interested, here are some useful links.

Wikipedia explanation of color temperature, understand what a 20,000K bulb really is.
Color temperature - Wikipedia, the free encyclopedia

Excellent article showing the spectral analysis of a metal halide bulb.
Aquarium Frontiers On-Line: Feature

[jhnrb]

Here are a couple links to our helpful articles that might provide some input. Hope something here helps for background.

http://www.livingreefs.com/forums/sa...ng-primer.html

http://www.livingreefs.com/forums/sa...-lighting.html

http://www.livingreefs.com/forums/sa...-advanced.html

http://www.livingreefs.com/forums/sa...-lighting.html

[bjohanson1234]

Originally Posted by reeffreak

I curious to know how you incorporate the slow transition from dusk to dawn.In my mine,that would seem like a gazillion timers.Is their an alternative to the bulky outlet kind and the digital ones that can transition the amount of LEDs needed for a more realistic day cycle?

Im not sure how bdejong would implement it but i would try to desing a timer with a pulse width modulator that would change the persent of time the LED is on versus off. Lets say during the first hours, it would tell the LED to be on for 10% of the time. This would be like 1 millisecond on 9 milliseconds off. then the next hour bump it up to like 30% and so on untill it is on 100% for the peak mid day hours then gradually go back down until only the moon lights are on.

Brian

[bdejong]

(Read a few posts back, I talk about using a PWM controller)

On the transitioning of the light it would be just like described, using a PWM controller (basic in even the smallest micro controllers) I could duty cycle the leds from the main ones to the moon lights in a nice smooth transition.

Here is a screen shot of the spectral response as the light sits right now. It is reading at about 6700K. I am working on the supplementary BLUE LED bank right now and hope to have it installed in a few days, This should bring up the color temperature as well as the contribution to the blue portion of the spectrum. I am also looking into getting a set of higher color temperature White LEDS to start out with.

This is the baseline so that we can compare the light as I make changes. It should be interesting.

[jhnrb]

Very interesting thread. Keep us posted on your progress.

[AndyB4784]

There was an interesting article in Advanced Aquarist a few months ago that you may want to check out regarding LED lighting. I think that they tested the Solaris LED fixtures. Advanced Aquarist's Online Magazine - Product Review: A New Horizon in Lighting: PFO's Solaris LED System

[bdejong]

Great link, thanks. I am using the same equipment, although a better spectrometer (HR2000-High resolution instead of the standard SR2000). I am hoping to spend some time in the lab this weekend installing the complimentary blue LED's.

I do have to take exception to their statement that using the Philips LED was a good choice. The XLamp would have been a better one hands down. (Read a little company pride into that statement)

Think about it though, a light with only 25 devices was fairly equal to the 250 watt MH bulb. Only using 75 watts of power its a fairly large savings not only in heat generation (which is wasted energy) but also in power consumption. While power consumption is not a huge factor on a small tank like mine, I can image that it could be when you start looking at a 150-200 gallon tank where you are using several of the big daddy 400 watt MH lamps.

I will post more later, for now I have to get to work.

[reeffreak]

I'm fascinated how this works out for you.Always like the shimmer of MHs but not the heat or electricity consumption.,since my limited expertise and income I can't be an experimentalist.

keep us updated on your progress and good luck.

[bdejong]

Here is your update. I added 10 Royal Blue LED's to the mix to bring up the color temperature. The measured color temp is approx 17,500K. This is an average since at certain measurement points the spectrometer could not calculate the CCT.

As you can see the blue is peaked now. The color in the tank is great, not over blue but definitely more white.

The extra blues had to be mounted on the sides, so I am expecting that when I make the new housing I will be able to remove a few of them to bring the power consumption down.

All of the LEDs are running at only 350ma each. The light housing is mildly warm to the touch and is mounted about 4 inches above the water. There is no heat transfered to the water. Since reading the review article I am now monitoring the temperature differential from light on to light off. I have yet to notice more than a degree difference.