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How to choose an LED light for your planted aquarium

Art

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  • Oct 29, 2022
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    Miami, FL
    One of the things I'm studying at the moment is lighting technology for the planted aquarium hobby. When I started, the creme-de-la-creme was metal halide lighting. Dupla has the coolest around. Most of us mere mortals had to make due with fluorescents (and, no, it wasn't the T5s you have now).

    Today we seem to be divided by the T5 devotees and those that prefer the tech-forward LEDs. There is no doubt we're in a much better space when it comes to lighting. What's more, today lighting is relatively cheap with lower-cost fixtures producing decent results. After all, most light will grow plants, is the often said comment.

    Well, that may be but that's not what this thread is about. I want to get into some of the science and theory behind lighting for a planted aquarium in the hopes that we can come up with objective criteria that we can then apply to fixtures when shopping for lighting. This will allow us to compare different brands and see if any additional cost is worth the difference. Let's be educated consumers in our hobby.

    So, first things first. I contacted several light manufacturers and asked if they had any reports or studies that they could share with me about proper lighting for a planted aquarium or aquatic plants in general. Every one told me no. I then asked my friend Balazs from Green Aqua who also told me he didn't know of anyone who was actively studying this subject. Frustrating.

    I realize some of this has been brought up in various sites that are scattered across the Internet. Let's focus our discussion here on the latest thinking. If you know of any relevant data, please post it here.

    Let's start this journey by establishing the criteria needed to judge lights.

    Criteria to use to compare LED lighting for the planted aquarium​

    I propose that we use the following:
    1. Light spectrum - does the light provide the light spectrum that is most beneficial for photosynthesis and for visual appeal?
    2. PAR - does the light provide optimal PAR to optimize photosynthesis at the level needed?
    3. Light blending - does the light provide a blanket of light that blends the LEDs uniformly or does it create distinct areas of light leading to a disco ball effect?
    4. Light spread - does the light cover the entire aquarium or just areas?
    5. Heat dissipation - does the light have enough heat dissipation to extend its life?
    6. Warranty - all things break. How good is the warranty?
    7. UL certification - is the light certified by UL Labs for safety
    What do you think? Remove, add, others I didn't think of?
     
    Interesting. As I read thru your Criteria, I can't help but think of the LED's that I am currently using.
    1. Light spectrum - mine have a warmer tone and the available spectrum seems to appeal to many LED reviews. Strong Blues and Red with green.
    2. PAR - I can hit 200 in my tank - but prefer not to
    3. With my diffusers, the colors seem to blend nicely and there really is no disco effect
    4. With the 2 lights above a 48"x18" tank floor, I honestly don't notice any hot or cold spots
    5. the lights have internal fans. If the TV is off, you may notice them at 6' away. If the TV is on, you will never hear them
    6. Hmmm, I think 1 year
    7. Honestly would have to review, but I believe the answer is yes.

    The item not discussed, but one of the selling points for me. With the associated app, I can create any amount of light desired over a 24 hour period. In the early morning I get just enough light to see in the tank. The ramp up or down can contain an almost unlimited number of points. At any time, I can manually turn the lights on to any level or color (within reason) I choose - just by logging into the app.

    As for growing plants, the lights likely can provide whatever is needed. Have I learned how to harness all the power - no.
    Radion XR15 Spectrum.JPG
     
    Last edited:
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    Hey thanks. These are all good points.

    So I'm a gear and tech junkie so trust me I love the apps. My concern when I think about it, is what impact are we doing with our ability to change the power going to the individual colors. Sure I can make it burple, add lightning, simulate a storm in the Southern Pacific islands, but am I messing with the spectrum needed for photosynthesis.

    So here is the spectrum that most agree is what is optimal for photosynthesis:
    Fig2.41-Chlorophyll_ab.png
    This is ADA's Solar RGB's spectrum:
    ADA Solar RGB 2-500x500.PNG
    Compare them to the spectrum chart you posted. This is part of why I'm doing this. I want to make sure that manufacturers are using science to base their products instead of just marketing speak.

    ADA is using some of the more recent studies that show that green is also important with photosynthesis and it does highlight the green in our aquariums. It also has 160 LEDs packed into the unit with a diffuser to blend the light. But like most, I can't find PAR numbers on it.
     
    As I started to read your reply, I was thinking about the Green portion of the spectrum and that I had read more about the importance of green light. Then of course, you added the comment :)
    Spectrum wise, I don't feel my lights have enough blue. If I had a choice I would switch 1 or 2 warm whites for more blue LEDs. (feel I am a little shy in the 420-470 range).
    Another question I have to ask about my lights, and more specifically the spectrum - was that spectrum taken at the surface or thru 20" water? Of course they will never tell you.
    As for a lightning storm or cloud effect, my lights can do it. Don't know if I ever actually used them.
     
    The current trend is shifting to all LED lights containing RGBW LED Diodes. The better ones even have UV and IR. You can now dial in any spectrum and even pinpoint certain wavelengths. PAR is pretty easy just turn the light up to say 100%, or down to 25% for less PAR. Its funny only a very few manufacturers show actual PAR data for their lights. You would think this is a standard in today's day and age. Light blending and spread are not as good on the cheaper lights out there.
     
    Another question I have to ask about my lights, and more specifically the spectrum - was that spectrum taken at the surface or thru 20" water? Of course they will never tell you.
    This was one of the questions that bothered me and why I reached out to the manufacturers for science behind what they are doing. It is plausible that aquatic plants may have different photosynthetic requirements given the fact that water must travel down through water. Could it be they are more adapted towards blue light as that would penetrate deeper?
     
    The current trend is shifting to all LED lights containing RGBW LED Diodes. The better ones even have UV and IR. You can now dial in any spectrum and even pinpoint certain wavelengths. PAR is pretty easy just turn the light up to say 100%, or down to 25% for less PAR. Its funny only a very few manufacturers show actual PAR data for their lights. You would think this is a standard in today's day and age. Light blending and spread are not as good on the cheaper lights out there.
    Thanks, Steve.

    For those that don't know, RGB stands for red, green and blue LEDs. The W, of course, stands for white. For a long time, it was cost prohibitive to build a pure white LED so manufacturers would turn up all three RGB which produced a kinda white light. Now, with better technology, a pure white LED can be produced that is only slightly more expensive but brings a truer white. The issue is that the white LEDs can come in warm white, cold white, or notr white. I've seen "ultra" white LEDs that come in at 8000K.

    Notice the difference here. The first picture is from a Twinstar RGB only.
    rgb-led.jpeg

    Now this is with RGB+W (ultra):
    weisse-led.jpg

    This is from Aquasabi - white or RGB lighting?

    Do any of us know what our fixture has? How many LEDs?

    As far as being able to control the LEDs, do you think this is wise? I love to be able to control but for this I think Kessil has it right. They have a standard spectrum that you can't change (Kessil logic). This makes sure you don't screw up what works for the plants. Then they let you change how it looks to you visually only. This seems like a nice compromise.
     
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