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LED Height

Discussion in 'General Discussion' started by Actuary, Sep 20, 2011.

  1. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0

    Well I finally got around to finishing my DIY LEDs. There are 108 3W Cree LED's (72 RB/BL and 36 CW/NW) mounted about 13 inches above the waterline. My tank is a 180g 72x24x24 SPS tank. They are replacing 2 400w MHs and in terms of brightness (at least to the human eye) it looks pretty comparable. I realize there are intensity differences between LEDs and MHs so I just want to make sure I get these mounted at an appropriate height. 


    Here's how it looks from the front:



    /Portals/0/activeforums_Attach/IMG_4582.JPG







    And from the back:



    /Portals/0/activeforums_Attach/IMG_4585.JPG





    Any advice would be appreciated, thanks!
     
  2. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0
    Figured I should probably add that the blues are driven at 850mA and the whites are at 1.3A. The blues are currently dimmed at about 90% since I thought things looked too blue for my liking at 100%.
     
  3. xroads Veteran Reefkeeper Vendor

    La Porte City, IA
    Ratings:
    +1,014 / 6 / -0
    Check it with a par meter as it is easy to burn your corals with LEDS. If anything, dim them down & slowly ramp them up.

    Nice!

    Craig
     
  4. iaJim

    iaJim Inactive User

    775
    Ratings:
    +0 / 0 / -0
    I agree with Craig on the intensity. When I went from MH to LED I thought I had a comparable brightness to my eyes. My corals suffered until I backed it off down to about 35% and slowly brought it up to 65% as a top. Now my green slimmer is growing out of the water. Great problem!
     
  5. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0
    I've never used a PAR meter before. Anyone in the IC/CR area have one they would be willing to lend? What kind of values should I be targetting near the top and bottom of an SPS tank?
     
  6. xroads Veteran Reefkeeper Vendor

    La Porte City, IA
    Ratings:
    +1,014 / 6 / -0
    Since you are a member, you can borrow the one from the store if you would like for a couple of days.

    You dont need monster high par to grow SPS. 150-200 at the bottom is sufficient
     
  7. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0
    That would be awesome. I've been meaning to make it up to the store at some point since I moved out this direction since I've heard nothing but great things. What kind of hours do you have?
     
  8. xroads Veteran Reefkeeper Vendor

    La Porte City, IA
    Ratings:
    +1,014 / 6 / -0
    11-7 M-S 11-5 on Sunday

    Call first to make sure someone else isnt borrowing it. Sometimes we are there early & late too

    319-883-8028
     
  9. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0
    Thanks! I suppose I should probably also get an address as well. I think I'll try to come in next week to pick it up if that works for you. I'll just turn my LEDs down quite a ways to play it safe in the meantime.
     
  10. xroads Veteran Reefkeeper Vendor

    La Porte City, IA
    Ratings:
    +1,014 / 6 / -0
    7112 La Porte Rd in Washburn, 2 miles south of the casino on hwy 218
     
  11. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0
    Thanks. Now I'm thinking I should probably get an apex controller hooked up so I can play with the settings to get a better understanding of the relationship between PAR outuput and dim settings. I probably don't want to just turn my analog dimmers down to an appropriate PAR level and call it good since I won't be able to know what dim % I'm at. I'll get an apex jr and vdm module ordered pretty soon here and hopefully I'll be able to get the PAR meter from you next week.
     
  12. Actuary Well-Known ReefKeeper

    705
    Adel, IA
    Ratings:
    +145 / 1 / -0
    I finally managed to pick up the PAR meter yesterday and played around with different light settings to dial in to an appropriate PAR. My one concern is I've heard that blue LEDs have their PAR underestimated with PAR meters.

    I have a 2:1 B:W balance with my LEDs with blue at 70% and white at 60% and I'm reading about 200 at the sandbed and around 500 at the top of the rockwork. Am I going to end up scorching everything or is the error on the PAR meter somewhat trivial?

    By the way Craig I was extremely impressed with the store... that was the first time I've made it over there. I'm also impressed that I was able to contain myself to picking up only 3 frags!
     
  13. Big D Well-Known ReefKeeper

    889
    Center Point
    Ratings:
    +3 / 0 / -0
    Green Star Polyp (Pachyclavularia)
    Lighting
    (Sprung value) 3-9
    (PAR minimum) 300
    (PAR average) 600

    Frogspawn (Euphyllia)
    Lighting
    (Sprung value) 3-8
    (PAR Minimum) 300
    (PAR average) 550

    Acropora (Acropora)
    Lighting
    (Sprung value) 4-10
    (PAR Minimum) 400
    (PAR average) 700

     
  14. Bud Loves Bacon Website Team Board of Directors Leadership Team GIRS Member Vendor

    West Des Moines, IA
    Ratings:
    +1,821 / 14 / -0
    I'm no expert here, but from what I have read the perception of brightness is what gets people into trouble when switching from MHs to LEDs. You need to dial those back, way back. 750mA for the blues and 1.0A for the whites is probably even too much.

    LEDs get more efficient on a lumens/watt basis as you dim them also. So dimming to 50% of wattage will be less than 50% decrease in lumens.

    And yes I've also heard the PAR meters don't measure blue accurately. Our eyes perceive blue as brighter also, this is something newly discovered. Well actually one guy has been saying it for 25 years and now there's finally proof, there is a 3rd sensor in our retinas besides rods and cones. Can't remember what the 3rd one is called, but now you will hear about photopic and scotopic lighting, the latter being related to the sensor in the eye that perceives blue light as brighter. So in terms of house or office lighting, a 5000K or 6500K lamp (T8) will be perceived as brighter than a 3500K of the same lumen output.

    Not sure how this rambling relates to LEDs except that you can't necessarily trust your eyes when trying to make LEDs look like your MHs. Tune them way down.
     

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