Underwater lighting

[lamontcarter]

I was wondering if anyone has ever thought of using fiber optic cables as a way to move the source of light below the waters surface in their tank. Wouldn't this make the light normally bounced off the surface of the water actually useful? Also it would be easier to light specific spots?

[Reefy.Dave]

first thing that comes to mind is rope light from the christmas section. a buddy of mine was using them in his pond that he has and they work wonderfully.

[dogstar74]

Why not use solid acrylic rods about 3/8 inch diameter and cut the end at a slight angle. Then hit the end with a High power LED. Just aim it where you want.

Cheers
Aaron

[lamontcarter]

that's actually an incredible idea, at last i think. could this be a bad idea?...having lots of light coming from very small points beneath the water, could it be damaging to the animals eyes?

[dogstar74]

Not as damaging as blasting 400W of MH glory into the tank. A focal spotlight probably would be better in my opinion.

[dogstar74]

Another thing you could do is mount the lights under the bottom of the tank. And run the fiber optic of your choice behind the rockwork to the specimen of choice.

Just a thought.

[username in use]

ooo, I like the acrylic rod idea. I think the key will be polishing the ends of the rod to get as much light transmision as possible. I also wonder if you could shape the end of the rod into a slight dome to spread the light out.

[lamontcarter]

That's a good idea also. What if you used end-glow fiber optic cable, to take advantage of the reflective foil lining the inside. Some par readings from a test for this would be cool. I think I'll start saving for that.

[ReefEnabler]

would that material be safe to submerge in a reef?

[lamontcarter]

I don't think so, but some acrylic tubes with a glued on acrylic end plate could waterproof them.

[lamontcarter]

Or coat them in melted plastic?

[Discustopia]

All this would be very art deco and such, not for the traditional, but still understand the intrigue.

my 2c is this - I have enough trouble keeping my tank clean, any light getting through the rods would quickly diminish as algae would grow very quickly on an underwater light source.

[lamontcarter]

Regular cleaning still wouldn't be that bad,if there was a considerable increase in light output in the tank.

[mdavis203]

That would work great for fuge lighting with zero added heat. Nice idea.

[lamontcarter]

Yeah that's an even better idea

[jrizo1]

i like the idea

[kcress]

Discustopia; Beat me to the draw. Cleaning nightmare I would think.

Plastic rods work by total internal reflection. It just so happens this works for a stream of water too. Also water flowing thru a tube.

You could keep the end clean if your light pipe was slowly having your makeup water flowing into it.

[dogstar74]

Part of what makes these "tubes of light" work is the refraction of light hitting the sides. At least I think so. Well, doesn't that gradient change when you take and put it in water. In other words. Although a fiber has good internal conductance in the air due to incidence of refraction or density changes in the material to air interface, wouldn't that change significantly when you make that interface from fiber to water? Boy I either don't know the terminology or am not explaining it very well, but when you look at perfectly clear acrylic in the open air, it's easily visable, but when you submerge it, it becomes almost impossible to see due to the refraction of the material nearing the refraction of water.

Does this post make any sense?
I guess a cheep experiment is in order. Does anyone have a clear acrylic rod that they want to cut about a foot to length and shine a high power LED through into the water?

Please post the results.
Aaron

[lamontcarter]

I agree, it's at least worth a shot.