LED Lighting Compendium

[Storm]

Could we make this a sticky? This is very useful information.

[samamorgan]

Originally Posted by Storm

Could we make this a sticky? This is very useful information.

That would be cool. Is this something a mod would have to do?

I have emailed all the manufacturers that I know of who sell led aquarium lighting asking for par cs distance data. Already have several replies, TMC notably said they would get right on it and give me the information in a couple days. So this thread may get much bigger soon.

[samamorgan]

Response from AquaticLife to my multi manufacturer email:

Thanks for thinking of us for the planted tank forum. I’m sorry to say but our current LED strips are not really geared for plant growth, they are weighted heavily to the marine side and even for the marine we are using them only for accent lighting or fish only systems. We are working on a freshwater version that we hope to release soon but again this would be used for a fish only system.

As for growing plants we will have some higher wattage LED soon and we can assist in getting PAR values, spectrums and additional details when the product is released.

Regards,

Dave Troop

Aquatic Life, LLC

[samamorgan]

Response from Tropical Marine Center to my multi manufacturer email:

Following your email of yesterday, I’ve taken some readings from two of the units we recommend for planted aquaria. These were taken using an Apogee Model QMSS meter. The lights are mounted 7” above the water surface (this is the height where we achieve the best balance between shimmer effect, light spread and sufficient PAR, given maximum water depth of 20”. For deeper displays or where higher PAR is required at substrate, the lights would be mounted closer to the water surface).

The readings I got were as follows:

AquaBeam 1500XG Ocean White (10 x 9000K Cree XP-G diodes):

231 PAR @ surface (7” through air)
161 PAR @ 3”
104 PAR @ 7”
78 PAR @ 12”
52 PAR @ 18”

GroBeam 1000 Natural Daylight (10 x 6500K Cree XP-E Compact PowerLEDS)

195 PAR @ surface (7” through air)
120 PAR @ 3”
80 PAR @ 7”
52 PAR @ 12”
41 PAR @ 18”

I’ve attached the relevant pages from our aquatics catalogue – if there is in further information you require, please let me know.

Kind regards

Gyles Westcott
AquaRay Lighting Consultant

[samamorgan]

Got a long response from EcoTech about their Radion light, no help there. This isn't surprising considering that they are marine geared. I won't post the whole thing as they said they havent done any research and it shouldn't be considered an official statement from EcoTech, but heres the overall statement:

Please investigate for yourself.

[monkeyfish]

Great thread, definitely sticky worthy. Subscribing as the next two tanks I have planned will be getting LED's for sure.

[samamorgan]

Added some educational information on spectrum pertaining to LEDs.

[madness]

Great thread. Not sure how I didn't notice it before.

[Hoppy]

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:

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.

Just because plants are green doesn't mean they reflect all of the green parts of the light spectrum. It means they reflect more green than red, primarily, and blue secondarily. Another reason plants look green is that our eyes are very sensitive to green, but not at all sensitive to red. But, plants absorb all parts of the spectrum to some extent. Most LEDs don't have the very high spikes in output that we see with fluorescent lights. The ones I have seen have a peak, for sure, but it is a broad one, and there is still a lot of light emitted that isn't in that peak.

Until we know how much PAR we are getting with various lights in various configurations it makes little sense to try to complicate matters by also worrying about PUR. PUR was of much more importance when it was hard to get enough light to grow plants, and anything that would increase the amount of usable light we were getting from a light fixture was something good to pursue. Now, the biggest lighting problem we have is having way more light (PAR) than we can easily use on our tanks. So PUR becomes much less relevant.

I find the collecting of PAR data for various manufactured LED light fixtures very useful, and I hope we can expand it eventually to include all such lights that are available. Let's not complicate it.

[samamorgan]

I actually added this because i see a lot of questions like "why wont my incandescent/actinic lights grow plants? I've got enough wattage!"

I know that light reflection and human eye perception is much more complicated that i made it out to be, but actually adding that information in there would just complicate the idea i was trying to get across. You can see in the chart that the other spectrums are absorbed by the plant to a point, but not at nearly the rate that the proper spectrums are.

Also, wouldnt this factor in quite a bit from emmiter to emmiter? I know a lot of fixture manufacturers order patented emmiters from cree that put out the spectrums they want. Those patented emmiters vs a regular cool white would be significantly different in useable plant light, right?

If you really think this complicates things too much or its really just not useful end-user information, i'd be glad to take it down. If you think it is useful and can think of a way to improve the information in a concise way, i'm all for editing it. I'd like this thing to be a knowledge base from the community - for the community, not just from my point of view.

[manini]

Great information on LED lighting. I am about to begin my experiments on the AI Sol product on a 18 gal tank. Cant wait to see what kind of results I will be getting.

[samamorgan]

Originally Posted by manini

Great information on LED lighting. I am about to begin my experiments on the AI Sol product on a 18 gal tank. Cant wait to see what kind of results I will be getting.

Nice! I kinda wanted to get that fixture myself, but it's so much moneys!

[WingoAgency]

Originally Posted by manini

Great information on LED lighting. I am about to begin my experiments on the AI Sol product on a 18 gal tank. Cant wait to see what kind of results I will be getting.

That seems VERY OVERKILL! 24 3-5W over a 18G! Do you mean the nano?

[samamorgan]

Originally Posted by WingoAgency

That seems VERY OVERKILL! 24 3-5W over a 18G! Do you mean the nano?

I thought this too, have to hang it pretty high :p

[akpoly]

I have some TrueLumens that I just got. I'm waiting for my hands on a par meter. I can let you know what those get once I find out.