LED Wattage / screen size calculation

[koola]

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?

[RkyRickstr]

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

Info is outdated.

[Floyd R Turbo]

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.

[koola]

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)

[MorganAtlanta]

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".

[koola]

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.

[koola]

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.

[SantaMonica]

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

[Ace25]

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.

[djmatteo]

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!