Improved Color LED thread

Discussion in 'DIY' started by rygh, Oct 4, 2010.

  1. rygh

    rygh Supporting Member

    Hmm, I like the white disk idea. I will try that.
    I dialed the reds way back, which I needed to do anyway, so the funky red shimmer is not so bad,
    but I still want to improve it.

    I am still tweaking the color.
    Looks like the whites need to come down a little as well.
    Problem 1: the PWM response is totally not linear.
    So cutting PWM rate in half reduces light by much more than half.
    Problem 2: Nothing useful in the tank.
    All I have is white rock, white sand, and brown algae. Need some paint samples or something.
     
  2. rygh

    rygh Supporting Member

    Another thing I want to fix:

    I am getting a LOT of reflection off of the plexi shield, and off of the water.
    I expected it, but not really that much.
    Basically, the no-optics 120-deg lenses really drive light out sideways a lot.
    I may try to put short pieces of PVC pipe around the LEDs.
    Acting as a mini-reflector. About 3/4" long, which is the distance from heat sink to shield.
     
  3. yardartist

    yardartist Guest

    My fixture is about six inches above the water and it is bright to look across at. My plan is to shield the entire heat sink down to the water line in a reflective material. I'll try to get a photo tomorrow incase anyone has ideas on how to do this.
     
  4. JAR

    JAR Supporting Member

    Mylar comes to mind. Also mirror plexi.
     
  5. GreshamH

    GreshamH Guest

    mylar and saltwater go together like water and oil :) It's becomes useless very quickly :(
     
  6. GreshamH

    GreshamH Guest

    Flat white paint is one of the best options considering how other stuff ages.
     
  7. rygh

    rygh Supporting Member

    Yes, mylar and aluminum will be useless quickly.
    Although up in the lights, there is less salt, since it is fairly well sealed from the tank.
    So depends on exact application.

    Clarification:
    White paint is great at reflecting, and super easy. Better than aluminum, approaching mylar.
    BUT! It is diffuse reflection, not specular reflection, so light will bounce all over the place.
    So if you want to AIM the light with the reflector, it is not a good solution.

    For my turf scrubbers, I painted the outside of the acrylic with white paint, and it worked well
    as far as reflecting light on the inside.
    The only complication, you cannot use primer, so it scrapes off a bit easily.

    For the LEDs, the simplest thing that came to mind for me was the inside of a PVC pipe.
    White, highly reflective, has some UV protection, so it really should not change much over time.
    Cheap also.
    Basically, you simply cut off a short piece, and epoxy it to the heat sink around the LED.
    Probably 1.25" pipe.

    I will be doing some experimenting in a week or so.
    (Working on second driver board. When that is done, then next LED fixture)
     
  8. GreshamH

    GreshamH Guest

    My post was in direct response to some one else, and in HIS case the material was suggested to go all the way down to the tank. He's not trying to AIM the light as suggested in you post.

    easily solved using the correct spray paint. Krylon Fusion sticks pretty damn good to acrylic.
     
  9. rygh

    rygh Supporting Member

    Oops. Oh well, guess it can't hurt to clarify it anyway.
    :)


    Well yes, but that costs money. As opposed to leftover house paint.
    Hmm - spent near $1K on lights, but too cheap to buy the right kind of paint.
    ;)
     
  10. Tamazula

    Tamazula Guest

    You can buy stainless steel sheets that have one side polished to a mirror finish... that or a bright white paint/plexi/plastic are the best bet.

    At one point I was going to further employ the machine shop resources at my disposal to make a mirror finish sheet that mounted on my heatsink and had holes cut for each LED so that any light bouncing back up towards the heatsink was reflected back into the tank, but it seemed a little overkill.

    I get a lot of spillage through the glass of the tank itself (no optics) and that's with a closed hood. I can see how having a fixture without optics raised above the tank would create a considerable distraction.
     
  11. JAR

    JAR Supporting Member

    I have some sheets of 30"x30" 1/4 inch thick white plexiglass up for grabs
    for you if you want them Richard.
    I found them in front of the Gap store on Chestnut St. in the city.
    They had built display podiums and were tossing them.
     
  12. JAR

    JAR Supporting Member

    I had mylar on the back of my fuge for over a year. Salt was getting on it and it seemed to be holding up well. I have been using some mirrored plexi that I got from tap as part of a cover for my tank for over a year also and it's as good as new with getting sprayed by salt. I realize that this is not a scientific process but it has worked for me so far.
     
  13. rygh

    rygh Supporting Member

    I have a mostly closed hood, and my LEDs are only 2.5" from water, but it is still an issue.
    Probably due to sheer quantity.
    Both annoying from in front of the tank, plus I am losing a lot of light.

    Polished stainless is an interesting idea. I could pretty easily screw a thin sheet on both sides of the heat sink,
    so at least for forward/back lighting, it would be good.
    The bonus being that I can even bend it a bit, and it would actually reflect light back down properly, into tank.

    I thought mirrored stainless was a bit different blend as well. More chromium?
    I need to look at how it oxidizes over time with salt spray though. I have some stainless boat
    fittings that were shiny once, but not so much any more.
     
  14. Tamazula

    Tamazula Guest

    I would definitely coat it with something clear and salt-friendly... wouldn't want it exposed to the salt spray.
     
  15. rygh

    rygh Supporting Member

    I have received a couple of side questions like this:
    What is your opinion on recommended wattage per gallon / number of LEDs?

    Obviously a key question, and naturally, very hard to answer.

    If you want a really quick, safe, and expensive answer, the common rule is
    to go with about 3W per gallon, with dimmers. You will see that on RC and other places.

    I am running 1.8 W / gallon, and it seems slightly too bright.

    ---

    So what do you need? It depends:

    1) Actual "wattage".
    It is important to use your actual power, not the LED rating.
    For example, we often use 3W Cree LEDs.
    But we usually run them at 700 mA.
    And you need to look at the forward voltage at that specific current.
    So real wattage for that example = 0.7 A * 3.4 = 2.38W

    2) Coral requirements.
    Very basic - what types of coral do you plan, and what PAR do they need.

    3) How do you get the light to the coral.
    A very complex topic in itself.
    This is a function of coral (not tank) depth, fixture height, optics, acrylic shield.
    This can make a huge difference. Factor of 2, easy.
    So a lot of thought needs to go into that.

    4) Type of LEDs and how you run them.
    There is a big difference in lumens/watt between different LEDs. (XP-G / XP-E / Luxeon / etc)
    Plus, there is a big difference depending on the current. You get a more lumes/W at 350 mA than 1500 mA.
    Temperature matters a lot as well, but I assume these will be run cold.
    What also matters is the wavelengths used. But since most build will be predominantly RB + CW, that can
    pretty much be ignored.

    5) How long you plan to run the lights.
    Assuming you are in the correct PAR ballpark, a lot of tweaking can be done
    by simply changing the time the lights are on.

    ---

    So, like a lot of things, no perfect answer, only ranges and opinions.
    My opinion : Somewhere between 1 and 4. Not that helpful.

    ---

    A secondary problem : The normal real solution for regular lighting is to measure PAR.
    Unfortunately, most PAR meters, the cheap ones in particular, do not handle LEDs well, so
    the measurement is unreliable.
     
  16. rygh

    rygh Supporting Member

    Some quick pictures:

    Old tank. T5 + LED:
    [table]

    [img width=144 height=107]https://lh3.googleusercontent.com/_eaxg2H-5-nk/TXbCVAiQFNI/AAAAAAAAAQ0/ERlfZkr4f3U/s144/coral_tankold.jpg[/img]



    From Aquarium_Release



    New all LED:


    [img width=144 height=122]https://lh3.googleusercontent.com/_eaxg2H-5-nk/TXbCUhjC67I/AAAAAAAAAQw/_BNGm3WGGyQ/s144/coral_newtank.jpg[/img]



    From Aquarium_Release

    [/table]

    As you can see, a whole lot more blue.
    Also, the green "glows" a bit, so improved fluorescence. But hard to see well in picture.

    However: I keep having to hide all the coral in the back or shade.
    Out in the main light, even on the bottom, it closes up and hides.
    Need to turn the lights down a bit more.
     
  17. yardartist

    yardartist Guest

    I am at 65% and it looks like the upper limit until some SPS grows out to shade the LPS below.
     
  18. rygh

    rygh Supporting Member

    So here are some pictures to emphasize the red differences.
    I put in the standard API test card, since I bet a lot of people have that in front of them,
    plus it has a lot of colors.

    The blues/whites are on as normal.
    In the first picture, there are no reds.
    In the second, the reds are on max. (4 x XP-E red at 300 mA)
    In the third picture, I have a combo. From left to right : { no red / my choice / max red }
    Although I am turning red down a tiny bit more.

    On the third image, it is interesting to look at the right column - nitrates.
    With no red, the second orange 5 ppm still looks yellow.
    With too much red, the first yellow 0 ppm looks orange.
    With the right amount, it looks good.

    It is interesting the the green ammonia column does not look right on any of them.

    NO RED:
    [table]

    [img width=144 height=108]https://lh4.googleusercontent.com/_eaxg2H-5-nk/TXv5k2aZiII/AAAAAAAAARA/sVJDYY4OVmo/s144/no_red.jpg[/img]



    From Aquarium_Release



    MAX RED
    [table]

    [img width=144 height=108]https://lh6.googleusercontent.com/_eaxg2H-5-nk/TXv5lpDQqFI/AAAAAAAAARE/kuxoeBabLQc/s144/max_red.jpg[/img]



    From Aquarium_Release

    [/table]

    SID BY SIDE


    [img width=144 height=57]https://lh3.googleusercontent.com/_eaxg2H-5-nk/TXv7qM6H5EI/AAAAAAAAARI/AUuv7jwnckU/s144/side_reds.jpg[/img]



    From Aquarium_Release

    [/table]
     
  19. bmhair03

    bmhair03 Guest

    Thanks again for your info. Talked to Mike at Rapid. Was a great help. Ended up with a few more RB's closer to a 2 to 1 ratio. Plus Im going to get some extras to play around with
    Those fans are awsome . Super quiet. Now on to some sort of enclosure for the drivers.
     
  20. rygh

    rygh Supporting Member

    Great!
    Jameco sells some pretty cheap metal enclosure boxes.
    Reminder - drivers produce a fair amount heat as well. For yours, I think it was 15% or so.
    Make sure enclosures are well vented.
     

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