# question about lighting



## jrs (Mar 18, 2006)

The 10W small screw in compact bulbs are advertised as being equivilent to a 50W light bulb. Is this true and/or how misleading is this? What is the equivilent of their 20W?

They have a 6000K rating which is what I am looking for. I currently have 3 60W daylight bulbs in my pendants. Is the change worth it?

jrs


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## wtac (Mar 17, 2006)

Really tough to say without using a luxmeter to verify a manufacturers' claim. Watt per watt, "full spec" flourescents have a higher lumen output vs incandescents.

The CF bulbs in question would have a broader blue end of the light spectrum compared to incandescent with the blue coating, if it's the same bulb that I'm thinking of. On a spectral level, they'll have the spikes close to spectral peaks of the various phytopigments.

Is it worth it? With respect to replacement cost, it's marginal at best but considering _how_ the plants will grow and the color perception in our eyes, IMHO, they are worth it. If you're unsure, get one CF bulb and see how they compare.

JM2C


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## Plant Crazy (Mar 24, 2006)

The comparison that they're making to is to incandescent. So they're saying that the lumens of the 10W compact bulbs are equivalent to a 50W incandescent bulb.

Are you currently using incandescent bulbs to light your tank? If so, then I'd say yes, there are several benefits to change to compact bulbs: increased lighting efficiency, less heat, potentially longer bulb life. However, what is the size of your tank? The reason that I'm asking is that there appears to be a minimum light threshold, and the watts per gallon doesn't hold for small tanks (say, 10gallons or less). The article on Rex Grigg explains this issue:
http://rexgrigg.com/mlt.htm


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## jrs (Mar 18, 2006)

I have them over a 5' 75g tank. I had found 3 pendants at a yard sale for a good price, I think they were used to light some type of display perhaps at a convention or something. A major problem is that they have no type of conical reflector. They are rated for 175W each but I have 60W incadescent flood lights in each. In addition, I have a dual 48" light with a cool white bulb and a plant bulb (pinkish in color).
I have a wide variety of plants in the tank so I want to insure that I am able to hit all relevant parts of the spectrum.


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## Plant Crazy (Mar 24, 2006)

With 10W compact fluorescent screw in bulbs (so 3 x 10W), you probably won't obtain sufficient lighting. If you're still interested in going compact fluorescent screw-in bulbs, then I'd go for a higher wattage. For example, Home Depot or Canadian Tire carries the 25W (or is it 27W?) screw-in bulbs. You could order from a specialty lighting store, much higher wattage bulbs. Check out this page that I pulled from a google search, as an example of the higher wattage bulbs: http://www.naturallighting.com/order/store.php?crn=612
As you mentioned however, the absence of a good quality reflector will somewhat limit the efficiency of the lighting fixture. Nevertheless, screw-in compact fluorescents are an easy, and affordable way to go.

As for the colour spectrum (measured in Kelvin), what I've often heard is that the spectrum is not that important for plant growth. It sounds rather counterintuitive, however from empirical experience, the majority of planted tank folk seem to do well with bulbs ranging from the lower end (e.g., 5,000 to 6,000K) to the upper end (e.g., 10,000K). Some claim that a certain Kelvin will promote redder plants, or reduce the incidence of algae. Personally, I've used 6,5000K, and 10,000K, and haven't noticed any difference in plant growth. Most people choose the spectrum of colour that they find most visually appealing (6,500K for a yellower light, 10,000K for a whiter light). So, in terms of buying compact fluorescent screw-in bulbs, any of the ones found at the hardware stores such as 'cool white' or 'full spectrum' should be fine for plant growth.


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## Ciddian (Mar 15, 2006)

Are these the engery saver type blubs?

I cheaped out and just popped some into my Incandecent hood over my 10 gal and the plants are growing like wild.. Duck weed is a PITA! lol...

Very interesting posts guys! Sorry i cant be of any help jrs :3


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## wtac (Mar 17, 2006)

Think of "white light" as a blend of all the colors of the light spectrum (ROYGBIV). Green plants are green because the various phytopigments absorb red, orange, yellow and blue wavelengths and reflect the green...thus we see a green plant. Red plants absorb all but reflect red light wavelengths.

Plant Crazy: my mind was on differing tube shapes (straight/"U" vs coil), restrike of light to adjacent tubes and the %of light that is actually going into the aquarium. A few of us were discussing this topic a week ago...LOL. You're bang on in your last post.


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## Plant Crazy (Mar 24, 2006)

wtac said:


> Plant Crazy: my mind was on differing tube shapes (straight/"U" vs coil), restrike of light to adjacent tubes and the %of light that is actually going into the aquarium. A few of us were discussing this topic a week ago...LOL. You're bang on in your last post.


Yeah, I believe that with the spiral configuration, there is more light lost to restrike, than versus a straight configuration.

Jrs, there's some very useful posts about spiral compact fluorscents on plantedtank.net:
http://www.plantedtank.net/forums/lighting/28236-spiral-lights.html?highlight=bulb+shape
Here's a link with a DIY spiral compact fluorescent hood:http://www.plantedtank.net/forums/lighting/24944-diy-spiral-fluorescent-fixture-46-bowfront.html?highlight=bulb+shape
And a very short thread about reflectors: (AHSupply sells parabolic reflectors, which optimize the amount of light entering the tank) http://www.plantedtank.net/forums/lighting/857-question-about-reflectors.html?highlight=bulb+shape


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## Ciddian (Mar 15, 2006)

Wow its interesting to see the pendant style bulb... That is a first in my books  
That top is quite itimidating.. LOL


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