Not Quite Sold on LED Lighting

Discussion in 'LED Aquarium Lighting' started by Mr. Bill, Feb 2, 2012.

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  1. m2434

    m2434 Giant Squid

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    I don't see where you have defined anything. If you say, "Looking at 1:1 RB and CW spectra for LED's versus a metal halide you see alot of differences. " Well, which halide? My point is, until you define exactly what you are talking about, it is a generalization at best.


    They don't have nearly the same peaks. The phoenix has it's main peak at 450nm (as does the CREE Royal blue by the way). The Giesmann has major peaks at about 420nm, 430nm, 540nm and 575 nm. The Hamilton has it's major peak at 450nm. The XM at 420nm.

    What the heck do these have in common? Regardless, you can get LEDs with significant output in all of these ranges.

    That is what you are saying, but my issue was with generalizations. People need to be clear about what they are talking about. If someone says "I put an LED on my tank and the corals shrunk" and then I put halides on and corals got big. Why was there a difference? Is it because corals shrink when there is too much light, to limit surface area and expand when they want more light, to expand surface area (they do do this....). Or is it because there is some magical unknown property of LEDs that makes corals run away (there isn't light it light). So, when people have trouble, it is beneficial to describe exactly which LED, versus which halide, in order to understand why there may have been a difference. Generalizations are just that...


    "ALL LEDs" don't have a narrower spectral range. Spectral range depends on the specific LED and the specific light you are comparing it to. Many "white" LEDs use the exact same phosphours as many T-5s and have almost the exact same spectral output.... Again, the devil is in the details...

    If they have the same spectral properties and same intensity (PAR) and all other things are held equal, they will have the same growth. There is no way to deny that. If you have the same light any difference can't be attributed to light. If you don't have the same light, that is not generalizable to "all leds" that is generalizable to the leds you are currently using....

    However, that said, much has been studied and written about response to light. Light does not need to be the same, to get the same growth. Assuming there are no other limitations, essentially all the light has to do is get the zooxanthellae to photosaturate (that is work at it's maximum efficiency) and not photoinhibit (that is start to shut down due to too much light). The fact of the matter is, corals are very good at photoadaptation, you can get this response with a range of light.
     
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  3. tharsis

    tharsis Peppermint Shrimp

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    [​IMG]

    This comparison of Crees and cheap LED's shows a similar spectral output, just vastly different intensity.

    i agree that if PAR and spectral output are identical, the coral doesn't give two @#$ what the source is. But what I am saying is that the trouble with LEDS right now is gettting the right combinations.

    My generalizations with LEDS is that they ALL need to be combined to generate a spectrum regardless of brand. There is no LED on the market (that I know of) that has a complete spectrum. How they are combined and the resultant growth from different combinations is still being explored and this is where there is room for improvement.

    So yes it is a generalized statement...but there is no other way around it. It is the same issue regardless of brand.

    To be more specific... If I took 1:1 CW and RB Cree LEDS and then took a wide spectrum Cree fixture which included UV/red/green etc, would you expect the coral to exhibit the same growth under identical conditions? If your answer is no or I don't know then I feel that my initial statement is true. Until testing can be done to show that a given combination of a specific color and brand of LED's provides the same growth of an equivalent metal halide (in terms of spectrum) than you can't say that led's are equivalent.
     
    Last edited: Feb 2, 2012
  4. Atticus818

    Atticus818 Eyelash Blennie

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    So I am totally gonna dumb down this conversation right here.... I watched both videos, and his "final" update about the 90g over which he has 2 radions. He shows comparison shots, first halides then LED, and marks how great the growth was under the Radions.

    The trick for me was that the color of the coral in every single shot had gotten much worse under the LEDs...

    Now for my question; Is this just a difference in how the camera pics up light (Seen people complain about how hard it is to photograph LED tanks) or has the coral actually just lost a good portion of its color and people are happy due to the growth trade off?
     
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  5. m2434

    m2434 Giant Squid

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    What do you mean, not "full spectrum? The plot you just posted is full spectrum. It may not have intensity at certain regions. For example, there isn't significant output at 420nm. However, do you think lack of output at 420nm will result in less growth than halides. The Phoenix 14000K does not have significant output at 420nm and it is a metal halide...

    On an interesting side note, I've not found the need to acclimate corals, when going from Phoenix 14000K MH, to CREE Royal Blue dominant LEDs systems, of similar PAR. CREE Royal blue LEDs and the Phoenix 14000K are about 75% identical though with regards to spectral output.

    The graphs posted above vary by as much as 40% (or more) for given spectral ranges. That isn't trivial. I think your saying the slopes are similar. That may be true, but then why is the slope more important than the actual spectrum? They are full spectrum i.e. they cover 400-700nm.

    1:1 CW RB is full spectrum. It has plenty of red and green. More so than many halides. UV is a poison and inhibits growth. So, adding UV, will either have no effect on growth, if the coral has sufficient sunscreen pigments to block it, or if more than the coral can block, then it will decrease growth.

    Green and red may make corals look better to us, but there isn't much green and red in the ocean. It's not a color range that we would expect corals to be well adapted to for growth, although, I expect they can adapt to it.

    I would say that otherwise, if photoadapted to that given spectrum and there is sufficient intensity to photosaturate (and no other limitations), and there isn't too much UV, then yes, they should have similar growth.

    Yes exactly ;)
     
  6. Mr. Bill

    Mr. Bill Native Floridian

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    Yes, the color loss was real. They mentioned it in the video. And when Mr. Saltwater Tank did upgrade to LED, it was not with the AI SOL.

    For me, the technology still has a long way to go. Will LED grow corals? Absolutely. Can corals keep their color? Under the proper spectrum, PAR, etc, again, yes. However, I'm not dropping $600+ for a non-modular, non-controllable system just to say I have LED, nor do I plan to spend $1500+ for top-of-the-line that may still need upgrades before it's perfected. When I can get a decent, reliable unit for a reasonable price with no assembly required, I'll look into it again. Until then, I'll keep buying T5HO tubes and beer. :)
     
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  7. Atticus818

    Atticus818 Eyelash Blennie

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    I should have clarified, I was not referring to the AI sol that they tested, but rather the Ecotech Radion that he moved his 90g to. Those side by sides showed the same exact color loss that almost every LED user has shown via photos IMO.
     
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  9. tharsis

    tharsis Peppermint Shrimp

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    Well I am glad we can agree on something :cheesy:

    As for the comparison of the Crees and Satistronics it is just a problem of intensity isn't it? Based on peak convolution, if I multiply the satistronic peak by some value the peaks would be the same. So if that number was 2, 2 sat leds would have the equivalent intensity and spectral range as the cree. If that number was 1.5, i would need 3 sats to every 2 Crees to get the equivalent intensity and spectral range.
     
    Last edited: Feb 2, 2012
  10. m2434

    m2434 Giant Squid

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    Coral coloration, assuming it is a response to light, and all other things are equal, is a function of high intensity, high energy light. In other words, corals color up in response to high intensity light, and for the most part (there may be a few exceptions, but not many), on the blue end of the spectrum.
     
  11. DBOSHIBBY

    DBOSHIBBY Sleeper Shark

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    I know ill prob get heat from the led lovers :) but I had 5 par38 nanotuners leds over my 65g and changed to a 6 bulb t5ho with all ati bulbs and my tank seems healthier than when I had leds. Coral color/polyp extention is getting better everyday.
    I didn't change any maintenance schedule or flow or anything. Just the lights. I feel the t5s out do the old leds by a long shot.
    Just my 2cents.
     
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  12. m2434

    m2434 Giant Squid

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    When I switched my T-5 supplemental lights, to an AI SOL, the corals under it colored up ::) As I said, color is a response to PAR. The Radion is twice the wattage of the AI and will have more PAR, over a wider area (I.e. don't look at the point estimates of PAR, look at the average over the coverage area, or at a particular coral you are comparing). I'll always expect healthy corals to have more color under more PAR.