# CF Direction



## aquariageek (May 27, 2006)

Which direction do compact fluorescents emit light the most? 
I read that they emit light perpendicular to the direction of the tube, so I would assume it is the direction of the red arrow above. Going with that assumption I have a 75 W Natural Daylight CF on top of my 5.5 gallon El Natural inside a parabolic reflector, therefore the top of the bulb is pointing at the water as in the picture below.










It seems that generally bulbs are mounted horizontally... is this becuase it is more space efficient?

So, Which is the best way to mount a spiral CF?


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## redstrat (Apr 3, 2006)

depends on your reflector. You have to match the correct reflector to your application. to optimize what you you may want to look into a horizontal mount with a reflector and raise it a little higher from the tank so the light spreads over the tank better for more even distribution of light.

also the spiral bulbs are a little inefficent for our application mainly because the shape causes the bulb to block a good portion of the bulbs output. This is why most bulbs made for aquariums are elongated and do not overlap, as well as creating even distribution.


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## dennis (Mar 1, 2004)

Technically, light is emmited from every direction equally, perpendicular to the glass. In any situation, the most amount af light that reaches your aquarium is tfrom the area of the bulbwith the most surface area. In your case, the blue arrow represents the direction on which a greater percentage of the light produced by the bulb will travel.

Hmm, maybe not the best explination. Imagine you are looking at the end of a straight tube, or at the eraser end of a pencil. Energy (light) radiates from every point along the surface of the pencil, so if you imagine light being emmited from the pencil as only a few waves, it would look like this *.

Make sense. Now to be really simple, if you bend the tube in half once (like a PC bulb) the sections of the tube that are facing each other will be hit with light emitted from the opposite part. ** The energy bounces around between the two surfaces of the bulb, changing from light energy to heat energy which escapes into the atmosphere. Rough guess, you loose 5% of the light from a single bend. Now spiral the tube around like in your light and you loose 5% from each side of each spiral and much of the light that is emitted into the cone of the light is lost. Even with a really good reflector, you're lucky if you get 50% of the light from this bulb. Your reflector will give even less.

sorry for the dragged out explanation. Basically, the way you have it mounted is least effective and only a small part of the tank is receiving any light, as is shown by the photo. I bet it looks brighter in person but it won't be. You'd be better off with 2, 25 watt bulbs, or better yet, a small florescent strip light. If you want low light, a single strip florescent hood/light for a 5.5 gallon works excellent for El natural, or you can get a cheap under cabinet light from Lowes/HD.


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## niko (Jan 28, 2004)

I think that with the reflector that you have you are getting the most of the worst possible design of fluorescent bulbs. The idea is to expose as much of the bulb surface and direct the light toward the water and you have done exactly that.

With a flat reflector above the bulb and the bulb placed along the surface of the water the actual light that reaches the tank is barely 40%! And these bulbs get hot, hot, hot!

The reflector helps you make the most of the spiral CF but as Dennis explained - because of the moronic design of those things most of the light just bounces between the tubes or inside the coil.

--Nikolay


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## aquariageek (May 27, 2006)

Thanks guys, that makes a lot of sense. I appreciate your detailed response dennis... that is just what I needed.  

At first I thought it was a good idea, but I notice the plants are really getting hardly any light from the bulb.

I want to keep it simple... so I may go with a single straight fluorescent bulb.


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## joephys (May 9, 2006)

Wallmart sells some bulbs that are screw in CF. They are strait not spiral, but there are still 4 tubes on it so its not the most efficient set up. Much better than the spiral bulbs though.


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## Jimbo205 (Feb 2, 2006)

If you can find them, I recommend the lights of america bulb Model # 2220. Natural Spectrum Light. I purchased some of these this past summer, and finally saw them again on their website last night. The price was not as good as what I paid in Wal*Mart this past summer, but until I find them again locally - that is the only place I have seen them (their website). The tubes go straight out and then bend back.


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## ruki (Jul 4, 2006)

I've played a bit with spiral and small folded compact flourescent bulbs. It's a brute force approach to make flourescent light, since the folds end up sending light into the tube again. But, even with this wasted light, it's more efficient than the incandescent lamp it replaces.

To my surprise, I found that a mini-version of the "high bay" reflector that you see in Metal Halide lamps inside works well. It's more of a half water mellon shape than the reflector used in the photo.


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