Basic info on fluorescent lighting

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Contributed by: removed user 08/18/04
submitted: July 6, 2003

This is a compilation of basic information on fluorescent lighting that I have gathered over a period of several months.

artwork provided by: ReSoNiC420

What is a fluorescent light?
A fluorescent light is made up of a glass tube coated with phosphor, which is filled with a mixture of gases. When electrical current is applied, it "excites" the gases, causing the tube to glow brightly. ie: to "fluores".

Why do fluorescent lights have different colors?
The tubing is coated with phosphor, which will determine the color of the bulb.

What diameters of fluorescent tubes are available?These are the most widely used diameter fluorescent tube size is T-5, T-8 T-10, T-12. Bulb sizes (meaning diameters) vary from .25 up to 1.5 inch, the larger in diameter the larger the fluorescent.

What length is most used?
There is a wide variety of lengths from 6 to 96 inch, the most widely used is a 48 inch fixture.

What wattage is there to use?
Fluorescents come in a wide range of watts any where from 4 to 214 watts that I have found.

Why does my bulb flicker?
Fluorescent tubes are rated by hours, these hours vary by the manufacture, the most common rated hours are from 6000-22000 hrs. The bulb flickering can also be caused by a poorly seated tube (poor receptacle contacts), a ballast or starter going bad or a tube wearing out such as shown in the photograph.

How do I dispose of these lights when they are broke?
Although commercially generated fluorescent lights are required by law, to be handled separately from general trash. Residents are allowed to dispose of them with the rest of their household garbage.

Where can I purchase fluorescent tubes, and how much do they cost?
Fluorescents can be purchased at all home improvement centers, hardware stores, and most pet supply stores or you can go to internet sites such as The cost may vary depending were you reside, but the typical cost is a few dollar's for a pack of two bulbs.

Who manufactures these lights?
These are the most reliable companies on the market today: Sylvania, Westinghouse, General Electric.

What are lumens?
Lumens are the unit of measure that state the amount of light output produced by a light source. The higher the lumens, the greater the light output. The standard fluorescent tube should produce at least (3000-3300) lumens.

How can I optimize the light output?
You can help reflect the light out of each tube, by using metal foil tape as a reflector, attached directly to the tube as shown in this faq. click here Using clear plastic safety sleeves over the fluorescent tubes allows you to recycle the metal foil reflective tape.

What is a Kelvin scale?
One way light is measured is on a Kelvin scale. A Kelvin scale expresses the exact color the bulb emits. Bulbs in the range of 2700 to 6500 on a Kelvin scale is ideal for growing marijuana. Plants respond not only to the quantity of light, but also the quality.
* artwork provided by: ReSoNiC420 (click chart to enlarge)

What color spectrums are available in fluorescent bulbs?
Fluorescent bulbs have the most range of spectrums than any other bulb. The spectrum comes in various spectrums, determined by the type of phosphor with which the bulb is coated. The following fluorescent types are as listed, along with what they may accomplish for you.

  • Full spectrum fluorescent bulbs have all the colors of the Kelvin scale. This bulb is good for vegetation stage. Note: This spectrum fluorescent is used in hospitals nationwide in helping people with "depression".

  • Wide spectrum fluorescent bulbs will restrict development of side branching, helps plants mature faster. This fluorescent is high in the red, orange and yellow color range. In fact, this fluorescent is the highest than all other fluorescent bulbs. As a matter of fact, this fluorescent is much like an HPS color range, which makes it the best all around choice for flowering stage.

  • Daylight spectrum fluorescent bulbs are very high (if not the highest) in the blue range on the Kelvin scale. This fluorescent promotes an arctic blue look. I suggest this fluorescent during vegetation stage.

  • Cool spectrum fluorescent bulbs will promote multiple side growth, nice green foliage. This fluorescent is high in the blue range, giving off a bright white appearance. I suggest this fluorescent for vegetation stage.

  • Warm spectrum fluorescent, will promote extra thick stems and branches, and will give you about 5% denser buds than other spectrums. This fluorescent is high in the red range on the Kelvin scale.

  • In the old school of fluorescent growing, an even mix of warm white and cool white tubes has been proven to be the best combination of light spectrums to use for flowering stage. If wide spectrum bulbs are unavailable in your area, then this is the combo to use.

    Do fluorescent tubes need air circulation?

    Fluorescent tubes do get warm, but not if they have adequate air circulation. A simple fan blowing over the fixtures as shown, will help a great deal to cool the tubes.
    If its done properly, any stray foliage that comes in contact with the tubes will not be harmed.

  •   Last modified: 04:55 - Jul 12, 2003  

    faq:1539 "Basic info on fluorescent lighting"