Wednesday, September 20, 2006

Cheap Lighting for Plants: CF Sprial Bulbs

Cheap, high-output lighting options for smaller aquariums are hard to find. Most are at least $80+ and if you've got a smaller aquarium, it's usually because you don't have the money (or the money for more space) for a larger tank. So, here's a cheaper alternative: Compact Fluorescent Bulbs in an Incandescent Hood. Using CF bulbs, you can put together a lighting unit that can give you up to 50 watts in the space of a 12 inch strip light. The benefits of such a unit are a low cost and comparatively high output and you don't have to buy the bulbs from an overpriced aquarium supplier. For this unit, you need:

  • An incandescent strip light - You can use either a full hood like the All Glass Economy Glass Hood (these usually only come in a 10 gallon size) or just the strip light, like this Perfecto Incandescent Strip Light. The benefits of the strip light are that it can be moved and used on any size tank, but it is harder to find in local pet stores and you need to either suspend it (not recommended) or put it on a glass top. It usually costs about $20.
  • 2 Full Spectrum Compact Fluorescent Bulbs - You want the screw in variety, not the ones with pins at the base. They also must not be larger in diameter than the light strip they will be used in. Usually, a 25W bulb is about the largest that will fit, unless you can find the non-spiral U-tube variety: then length and the maximum wattage of the strip is the limiting factor (most are 2 x 25W max). These bulbs are quite hard to find in a full spectrum color temperature. Wal-Mart stores often carry a "Lights of America" brand that offers them in Daylight 5500K. Alternatively, many online light bulb sellers, such as 1000bulbs.com or SpecialtyLights.com offer them in spectrums that will work.
There's no altering or assembly required, just screw in the CF bulbs, put it on your tank and off you go! There are a few important things to remember though. Do not expose the bulbs directly to the water. There should be glass or something in between protecting them from water splashes and condensation. Also, the higher wattage bulb you use, the more heat will be generated (more on this below). In a warm climate with no way of cooling the tank, this may cause temperatures to rise to unhealthy levels. This approach certainly offers the most "bang for the buck," but it is not the most efficient means of lighting your tank. Spiral bulbs are less efficient than linear tubes because light exiting the tube has the possibility of reflecting back into another part of the tube, or may just enter another part of the tube directly. This causes light loss and heat buildup and is known as "restrike." So all 50 watts are not entering the tank, but instead some light is being lost in the bulb itself. I haven't been able to figure out or find a figure on just how much light is lost, but it's not so significant that the light output is seriously diminished. The incandescent hoods often don't have any sort of reflector in them (some have a small metal reflector, but it doesn't do much) so some of the light is lost when it is absorbed by the light housing. Regular tin foil can be used to line the housing behind the bulbs which will slightly increase the light getting into the aquarium, but it will block ventilation, causing the bulbs to run much hotter and reducing their life.

If you are looking for the cheapest lighting option with the highest light output, you should consider a CF Spiral bulb unit. Be aware that it is not the most efficent option, many systems are available that offer highly polished and engineered reflectors that give you the same results with a lower wattage because more light is actually getting into the tank. However, these will definitely cost you more up-front.

Pros: Best "bang for your buck" for smaller aquariums, easy to replace bulbs


Cons: Uses more power, creates more heat, less light actually gets into the tank


Total cost: $48: $20 for Incandescent Stip Light, $8 per bulb, $20 for glass hood/canopy

7 comments:

  1. Hi, I wanted to say I like your blog a lot. I have found a lot of useful information for keeping and maintaining a planted aquarium.

    In this port you show how to build your own low cost light for growing underwater plants. Everything is correct accept the fact you mention about tin foil.
    Tin foil will actually scatter your light even more than a white piece of plastic.
    I am sure you have heard of Rex Grigg by now. He mentions on his website about using tinfoil as a reflector as being a horrible idea. This is because the foil is acting as a diffuser for the light. Rex also mentions a test for this. If you point a laser pointer, any kind, at the tin foil and look at the reflection you wont see much. Point it at a mirror and, well I think you know how a mirror reflects.
    A couple other ideas you can use as a reflector for your light is grabbing a reflector used in another light fixture if you have access to one.
    Or go over to your local hardware store and look for mylar. It's cheap and way more effective than tin foil.

    Good Luck.

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  2. You are correct that tin foil scatters light. However, in the context of cheap aquarium lighting, reflection is king. It's all about getting the most amount of light that would be otherwise lost reflected back downwards towards the aquarium. The light may be scattered, but it is still entering the aquarium. It may be slightly weakened by that scattering, but a whole lot more is entering the aquarium than would without the foil, offsetting the diffusion. To prove this with a laser, try shining it at the black plastic that exists in lighting hoods and see how much reflects. Then shine it at foil. Or, for a more rudimentary experiment, try lining a hood with foil and leaving another with black plastic, then see which is brighter. Although the light is spread out, it is still light that is entering the aquarium that would otherwise have been absorbed by the black plastic. Nothing else this cheap or easy comes close to matching the reflectiveness of foil. However if you are willing to spend more money and get only marginally better reflection you can try mylar. The ultimate key to this guide was minimal cost/effort and maximum output.

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  3. I understand you are trying to keep this DIY project as cheap as possible. But I think what is more important is getting more of the cheap light into the tank. The price difference between a sheet of mylar compared to tin foil is hardly any at all. You may be sending a few extra bucks, but those few extra bucks will insure that your tank receives much more light than you would using tin foil.

    In my opinion it is a waste of tin foil and time to use the tin foil for the lousy outcome it produces. (diffused light)
    I think you can still call your project cheap by adding a few extra buck for mylar and achieving a MUCH better outcome. Or just tell your readers to use white paint.

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  4. HI YOUR SITE WAS RECOMMENDED TO ME FROM SOMEONE ON AQUABID.COM A PLACE WHERE I SELL LOTS OF GREAT FISH FOODS.

    I HAVE USED THE SPIRAL LIGHTS AS SUGGESTED, BUT, IF YOU REALLY WANT TO SAVE MONEY, AND WHO DOESN'T, MAKE YOUR OWN STRIP LIGHTS USING, SOCKETS AND WHITE ALUMINUM GUTTER, YOU CAN GET AT LEAST 4-6 FROM 1 8 FOOT SECTION...UNDER $10. $1 EACH FOR END CAPS AND AND $3 FOR SOCKETS/WITH SWITCHES.
    AND YOU CAN USE HIGHER WATTAGE BULBS!

    BUT THE BEST DEAL IS THE LIGHTS OF AMERICA FLUOREX OUT DOOR FLOOD LIGHT, FITS MOST TANKS (I HAVE 4 ON A 55G.), IS WATERPROOF, FULL SPECTRUM, 250 WATTS FLUORESCENT
    65 REAL WATTS USED, AND AROUND $50

    ReplyDelete
  5. hi, i'm still an amature...learning about planted aquarium. your blog is great!
    about your DIY CO2 project...how do you stop the CO2 supply(say in the night)???
    sorry if its a silly thing to ask....:)

    ReplyDelete
  6. After reading this and other articles about the new Spiral Lights, I'm planning on building my own hood and light strip over my 150 Gallon. I was planning on using the plastic light sockets you get from home depot and probably put about 6 - 100 Watt 6500K Daylight bulbs across the top of my hood. My only concern is will 6 - 100 bulbs which are actually 26 watts each all be able to run off one plug?

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