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Thread: LED Wattage / screen size calculation

  1. #1

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    LED Wattage / screen size calculation

    I've read the excellent guide: Algae-Scrubber-Basics-The-Summary

    Tank size: 30cm3
    1 litre = 1000 cubic centimeters
    1 US Gal = 3.78541 Litres
    1 Inch = 5.08cm

    ((30*30)*30/1000)/3.78541=7.13 US Gal

    1. Advice from guide is 1 watt per 1 gallon so it's more than sufficient to use a 10 watt LED as below?


    http://item.taobao.com/item.htm?id=10584760366

    2. So my screen size should be;

    2-inch^2 = 4
    7.13-Gal * 4 = 28.52-area

    ratio of L:W (2:3)

    28.52 = 3x * 2x
    6x^2 = 28.52
    x^2 = 4.75
    x = sqrt(4.75)
    x = 2.1

    L = 2 * 2.1 = 4.2-inch
    W = 3 * 2.1 = 6.3-inch

    L = 4.2 * 2.54 = 10-cm
    W = 6.3 * 2.54 = 16-cm

    correct?

  2. #2
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    Screens are now sized according to feeding, not water volume.

    Info is outdated.

  3. #3
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    Also, your method of calculation is incorrect, I'm not sure where you are getting that but just start over.

    1) old method: 1 sq in of screen per gallon. So for a 7 gallon tank, you need 7 sq in of screen

    2) new method: 12 sq in of screen for each cube of food fed per day.

    With either one, if you have a tank that small, I would think a 12 sq in screen would be more that adequate. In fact you might be best with the HOG .5 for that small of a tank.

  4. #4

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    Can see my math is wrong, it was late haha

    Here's the math for single side screen;

    7.13-Gal * 2 = 14.26-In2

    ratio of L:W (2:3)

    Area = 3x * 2x
    6x^2 = 14.26
    x^2 = 2.376
    x = sqrt(2.376)
    x = 1.54

    L = 2 * 1.54 = 3.08-inch ( * 2.54 = 7.82 cm)
    W = 3 * 1.54 = 4.62-inch ( * 2.54 = 11.73 cm)

    and if I want it square;

    L,W = sqrt(14.26) = 3.78-inch ( * 2.54 = 9.6 cm)

    So has anyone experience with using the 10W LED?

    Edit:

    Also just to point out that the new method is quite close to that of the old for example;

    L,W = sqrt(12) = 3.46-inch ( * 2.54 = 8.79 cm)

  5. #5

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    If you are planning a one-sided screen, then you need 24 square inches per food cube. Something close to 5" x 5" or 6" x 4".

  6. #6

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    Quote Originally Posted by MorganAtlanta View Post
    If you are planning a one-sided screen, then you need 24 square inches per food cube. Something close to 5" x 5" or 6" x 4".
    Your correct or I feed them 1/2 cube per day... am not that mean.

  7. #7

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    Would like some feedback on a single 10W LED for this screen if anyone has tried before? Am probs going to take a shot at it given it's so cheap to try.

  8. #8
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    I think if you keep it 10 cm away from the screen, it might work.

  9. #9
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    That 10w light is WHITE light. Why not look for a 'Grow Light' that is red and blue? I would think they would be pretty easy to find in China as most of them are made there.

  10. #10

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    I recently purchased these:
    http://www.aliexpress.com/snapshot/204087149.html

    I went with 12:3 660 nm red, 450 blue

    I was advised however growth outside the primary light area wouldnt be to great, so something like this would work for smaller screen,

    They should arrive today and I will certainly let people know how they work! If you look around on ali baba there are several variants of lights, to many to pick from!

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