Lighting very shallow water

[xxmoorishmanxx]

i was wondering if lighting changes depending on the depth of water?

Reason i ask is this summer i would like to try to create a coral farm, with rubbermade bins, the ones i like are really long, wide, but very shallow only 4-6 inches. I was wondering since they're shallow i wouldn't need as strong of a light,

Not sure what i want to propgate i might start with xenia, and polyps things like that.

Any other advice is welcome

TIA JOSH

[diverdown69]

I honestly thought that lighting was dependent on surface are exposed to the light. I know it also varies with what species are in the tank as each will have a different light requirement...I think.
I'd be interested to see how you establish this coral farm. I know of a guy here in Corpus that does it in his basement, but I don't really know how he does it.

[xxmoorishmanxx]

im not planning anything big first i wanna see how easy it would be to propagate these specoes my tank has coral and i know the requirments for these species, more or less i wanted to know if i used a pc on a 6in. deep tank would it be more effective than a 18 inch deep tank.

what u mean dependant on surface air exposed to light

[diverdown69]

Originally Posted by xxmoorishmanxx

what u mean dependant on surface air exposed to light

Did I misspell it? I meant to say surface area of the water. I saw something the other day that gave a lighting requirement in Watts/square meter. I honestly can't even remember where I saw it. It may have been in this book I have by Moe. I found it in the Tx A&M Corpus Christi library and checked it out.

[diverdown69]

Found it. From Moe, Martin A. (1989) The Marine Aquarium Reference, Systems and Invertebrates (Green Turtle Publications, Plantation FL), pg 159-160.
There is an equation in this section that actually tells how to determine the total lux required over a given surface area. Here it is. Let me see if I can explain it the way the book does.
W=LA/EU
W - watts
L - lux (total desired over the surface of the tank or holding bin)
A - surface area illuminated (sq meters)
E - efficacy factor of light bulb (depends on type of bulb)
U - utilization factor (constant, value of 0.5 that represents the total light that strikes the water from the bulb)
The book goes on to give an explanation, but it really doesn't go into the effects of light attenuation in this section. I would think that attenuation would be negligible with a shallow depth.

[xxmoorishmanxx]

thanx for some info if anyone else has more or other ideas let me know

[ellisz]

I believe the depth has a bit to do with it as well. With a shallow container like that, you could get some cheap PC lighting.

I know when people get corals that need a bit more light, it is recommended to place them higher in the tank. That being said, a lot of people with 10 gal nano's use 96watt power quads. Crazy stuff. Look at reefcentral, there are people that do just as your wanting to do. I am going to use a 10 gal to grow some softie frags.

[RogerMcAllen]

Depth is definately a huge issue actually. You are completely right in thinking that you will need less intesne lights on a shallower container due to light diffraction as the depth increases.

On a side note, couldn't you almost set up a greenhouse and just use natural light?

[xxmoorishmanxx]

probably, but that would be super intense, i am really thinking of starting with one conatainer and seeing where that goes

[ellisz]

You can get CF bulbs in a mogul socket pretty cheap. I have a minibow5 running off a 19 watt CF bulb I got from HD. It is a 6500K bulb. Coralife makes a 20 watt 10k/actinic 50/50 bulb as well like this($12). You could use a clamp style light fixture which would be cheap. This is not the best setup but could be tried easy enough.

I was going to do something like this on my 10 gal but I think I am going to get a PC retro kit. I have an itch for a wood project

[xxmoorishmanxx]

thanx for the advice