LED Lighting Compendium

[samamorgan]

Originally Posted by Ibn

Custom LED fixture built by a buddy. Fan cooled by 2 10mm fans. Forgot the details of the bulbs and driver.

PAR readings from what's currently run (12 bulbs out of 18; first channel whites 100% output; 2nd channel 4 blues, 2 whites 25% output; 3rd channel all blues off). 7" above the waterline or 16" to substrate depth in the front

PAR readings taken with Apogee unit.

Thats a really sweet fixture! I'm a little jealous. Not really anything i can add to the starter post but someone might find it useful when digging through here

[bassmjm]

Any word on the tmc 500/600?

[kalawai2000]

Any word from Marineland?

[samamorgan]

Originally Posted by bassmjm

Any word on the tmc 500/600?

Originally Posted by kalawai2000

Any word from Marineland?

No need to ask me for word, as soon as i get any information from manufacturers I will update the page promptly.

[dewalltheway]

Originally Posted by samamorgan

Not all spectrums are created equal!
Analyzing photosynthetically active radiation (PUR)

One of the reasons LEDs can be so much more efficient than T5, compact flourescent, and even metal halide is spectrum output. The chlorophyll pigment is green in color, which means that it reflects the green spectrum of light to our eyes so we see it as green. This means that it absorbs all other spectrums of visible light. Check out this graph:
Attachment 40237
As you can see, plants absorb visible light very well between ~400-500nm and ~650-700nm. The absorbtion rate drops off significantly in the green and yellow spectrums.

LEDs put out very specific spectrums of light, which are defined by the manufacturer. LED manufacturers can fine tune emmiters to put out exactly the spectrum specified by the client. Since PAR meters measure light between 400-700nm, an LED array putting out less par than a broad spectrum flourescent fixture may actually be putting out more photosynthetically usable radiation (PUR).

Why is this concept important?
Say two LED emmiters read around 100 PAR on a meter. The first LED spikes highest in the 550nm range. The second LED spikes highest in the 450nm range. So while both emmiters have the same PAR value, emmiter two would actually grow plants very well because it is in a range that can be absorbed by the plant, while emmiter one would probably keep plants limping along, if they could even survive.

So when you are saying 450nm is that the same as 450 lumens because I have seen lumens abbreviated as lm and wanted to make sure I was reading the chart correctly.

[samamorgan]

Originally Posted by dewalltheway

So when you are saying 450nm is that the same as 450 lumens because I have seen lumens abbreviated as lm and wanted to make sure I was reading the chart correctly.

Nothing in this thread has anything to do with lumens. A lumen is a measure of light visible to the human eye, and has little to nothing to do with plants. Nm is nanometers, and 450nm is the measure in nanometers between any two crests in that wavelength of light.

This should help:

[Hoppy]

ATTENTION MODERATORS: This thread is getting harder to find now. It needs to be a sticky so we can locate the collected data on LED lights more easily. This has been mentioned by several people, but hasn't been done yet. PLEASE!

[samamorgan]

Seconded.

[bereninga]

Thirded! I've actually subscribed to this thread, but it should be sticky for sure. Very useful info here.

[redfishsc]

This is a fantastic thread. Absolutely fantastic.

I have frequently thought of doing this with DIY LEDs (single LEDs, no optics, standard drive current) for data for Hoppy to run through his magic brain since he's the most capable person I know for predicting PAR levels.

FWIW, since many of those units you linked to are using Cree and Rebel LEDs, here is a thread I started a while back of some spectral analysis of Cree, Rebel, Bridgelux, and Satistronics LEDs--- taken via the radiometer at UNC Wilmington. Those LEDs now sit over my own 45g planted and my reef.



Feel free to link my thread in your original post if you think it's useful.

http://www.plantedtank.net/forums/li...r-planted.html

Originally Posted by Hoppy

ATTENTION MODERATORS: This thread is getting harder to find now. It needs to be a sticky so we can locate the collected data on LED lights more easily. This has been mentioned by several people, but hasn't been done yet. PLEASE!

Agreed. MAJOR agreed.

[dundadundun]

Originally Posted by Hoppy

ATTENTION MODERATORS: This thread is getting harder to find now. It needs to be a sticky so we can locate the collected data on LED lights more easily. This has been mentioned by several people, but hasn't been done yet. PLEASE!

post reported and plea made. looks like it might have worked.

EDIT: thanks to the mod team.

[Gatekeeper]

Originally Posted by dundadundun

EDIT: thanks to the mod team.

That's an admin decision straight from the boss himself Kyle. Man, stickies are a rare thing on this forum, we don't hand them out like comps at a casino, that's for sure. You must be doing something right, keep up the good work folks.

[samamorgan]

Originally Posted by Gatekeeper

That's an admin decision straight from the boss himself Kyle. Man, stickies are a rare thing on this forum, we don't hand them out like comps at a casino, that's for sure. You must be doing something right, keep up the good work folks.

Thanks a bunch! I'm glad this is proving to be of use to people.

I'm still wondering what the community thinks, and Hoppy in particular, do you really think that the spectrum analyzation thing over-complicates things, or isnt helpful information? Is there a way to make that information more applicable?

[Hoppy]

Originally Posted by samamorgan

Thanks a bunch! I'm glad this is proving to be of use to people.

I'm still wondering what the community thinks, and Hoppy in particular, do you really think that the spectrum analyzation thing over-complicates things, or isnt helpful information? Is there a way to make that information more applicable?

I think it is hard enough to get an appropriate PAR amount for our tanks, without introducing another complication. Perhaps in a few years PAR will be easy to handle, and then we can move up to more sophisticated analysis of light needs.

At this point I don't know of any testing that demonstrates that a given level of PAR works better if the PUR is optimized vs. an ordinary T5HO or LED light. If it works better I would expect it to allow usage of more light without more algae. The odds on that are pretty small though.

[samamorgan]

Originally Posted by Hoppy

I think it is hard enough to get an appropriate PAR amount for our tanks, without introducing another complication. Perhaps in a few years PAR will be easy to handle, and then we can move up to more sophisticated analysis of light needs.

At this point I don't know of any testing that demonstrates that a given level of PAR works better if the PUR is optimized vs. an ordinary T5HO or LED light. If it works better I would expect it to allow usage of more light without more algae. The odds on that are pretty small though.

I see your point. I added a disclaimer to the post that hopefully people will pay attention to. I think it's valuable information, but you're right, it really shouldnt factor into purchases on the list.