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Question: Tuning The "spectrum" Of Led Lighting

Discussion in 'Lighting' started by evangemeren, Jun 29, 2019.

  1. evangemeren

    evangemeren Junior Poster

    Oct 5, 2013
    Likes Received:
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    8:03 AM
    I have a general line of thinking that I'm hoping someone out there can help me with.

    A number of today's LED fixtures offer the capability to "tune" the spectrum of the fixture by varying the relative output of individual LEDs on the fixture with different "color" outputs.

    I have two questions:
    1. Based solely on varying the intensity of individual LEDs of different "colors", does this ability really make a difference in health and/or growth rate of the plants?
    2. If so, is it possible to "re-tune" a fixture intended for Saltwater use and make it suitable for a Freshwater planted tank?

    The basis for my first question is simple: while it is clear that different frequencies of light can be more effective at meeting the needs of aquatic plants, it is not clear the degree to which you can actually impact the spectrum of the fixture simply by varying the output of individual "colored" LEDs within a given fixture.

    For example: on the current model of the Radion XR15FW PRO G2 from EcoTech Marine, the manufacturer claims that the fixture produces the "ideal" output across the spectrum for freshwater plants - heavy in the Red spectrum with a second peak in the Blue spectrum, etc. They go on to provide "five channel" control over the spectrograph to allow you to tune it to your specific needs - they provide independent control over the relative illumination of the "red", "green", "blue", "warm white", and "cool white" LEDs for this purpose. However, if you look at the actual physical hardware, out of 23 physical LEDs on the fixture 15 of them are either "cool white" or "warm white". They provide only 4 "red" LEDs and 2 for each "Blue" and "Green". Therefore, simply by adjusting the relative intensity of each of these groups of LEDs, how much are you able to actually influence the resulting spectrographic distribution of the resulting light output? I am skeptical for two reasons: (A) the relative number of LEDs is clearly biased towards "white", and there is no data that shows what the spectrum emitted by these particular LEDs provides, and (B) just because of the manufacturer's claim that an individual LED in the fixture is "blue" doesn't necessarily mean you are going to only get more light in the blue spectrum by increasing its illumination (it's clear that this is what they are implying, however).

    (NOTE: my use of the Radion in the above example is not in any way meant to disparage this product ... it's a great product which I use myself. It was simply the first example that came to mind).

    Does anyone have - or can anyone point to - objective data that shows the impact that varying the intensity of these "colored" LEDs within a given fixture actually changes the resulting spectrograph significantly?

    Assuming this is true, therefore, wouldn't it make more sense to buy the Reefing version of a given fixture since they typically have more "channels" that can be individually tuned? For example, sticking with EcoTech Marine products, the Radion XR15W G4 PRO (a saltwater version of the fixture I referenced above in my earlier example) still has only 23 LEDs but they are broken out into a greater array of colors (both "blue", "deep blue", and "violet", and adding "photo red" and "UV"). With the saltwater fixture costing only a few dollars more, wouldn't it be the better buy?

  2. Phishless

    Phishless Lifetime Member
    Lifetime Member

    Jul 13, 2017
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    3:03 AM
    #1 my vote would be yes. Plants ver. Corals, they have different needs many have said.
    #2 my vote would be yes. SW fixtures have also grown plants well.

    IMHO this is where viewing your plants comes into play.
    UV doesn't count much in the planted tank unless battling green water.
    WW LED's have a lot of red spectrum included.
    520nm LED's provide green to make the plants appear better to our eyes.
    Full spectrum LED's grow plants very well but who wants to view pink/purple plants all of the time?
  3. keval

    keval New Member

    Apr 2, 2020
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    8:03 AM
    Hi evangemeren

    I'm new to The Barr Report and I've just spotted this thread that you started almost a year ago. Are you still active on here? If so, we can discuss your questions.


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