Hoa G. Nguyen's Freshwater Planted Aquarium

Below is a comparison of the various fluorescent light bulbs I have been able to obtain. The numbers were taken from catalogs, on-line lists, or the bulb labels themselves. The prices listed are the lowest that can be readily found (excluding special sales), with the source given in the legends at the bottom. Drop me a note if you found cheaper prices or can help fill in the missing data or supply corrections.

I photographed the spectral images using a diffraction filter given to me by Wright Huntley, a fellow aquarist. Although I haved tried to keep most factors constant while making the spectra, they are not to be taken as accurate because the instruments are not calibrated (for example, I do not know the spectral response of the digital camera), and the spectra were made at different times, as the bulbs became available to me, which allowed more variations to enter the measurements. However, I hope they will give you a rough idea of the comparative spectral distributions of the bulbs.

The "Comparative Color" field is highly subjective. I lit the bulbs side by side, three at a time, and noted the color tinge. When a bulb is described as being "red" or "blue," the color is strong and you should be able to see that color when the bulb is lit by itself. When a bulb is described as "reddish" or "blueish," the color tinge is weaker, and may be seen as "white" when not being compared side-by-side with other bulbs.

All bulbs are 4-ft long, with:

• T8 = 1" diameter, 32 W.
• T10 = 1.25" diameter, 40W.
• T12 = 1.5" diameter, 40W.

Brand	Bulb	Part #	Color Temp.	Type	Average Life (hr)	Initial Lumens	Design Lumens	CRI	Cost & Source	Spectrum	Comp. Color
Coralife	Trichromatic		6500K	T12		3125		92	$13 G		Slightly Blueish
Duro	VitaLite Power Twist		5500K	T12	24,000	2340		91	$18 F,G		Greenish
GE	Daylight Ultra	F40SP65	6500K	T12		3050		75	$4 B		Blueish
GE	Chroma 50 (Sunshine)	F40C50	5000K	T12		2250	1870	90	$6 B,C		Yellowish
GE	Plant & Aquarium	F40PL/ AQ	3200K	T12		1900		90	$6 C		Red
GE	Shop- Lite	F40/ SHOP		T12					$1 J		Reddish /Orange
GE	SPX50	F32T8/ SPX50	5000K	T8	20,000	2800	2660	86	$3.45 A		Pinkish
Interpet	Triton	40W		T12		2200	2000	91	$22 G		Purplish
Kentucky Lamp	Ind. Grade Cool White	F40CW		T12	20,000	3050			$1 J		Orangish
PennPlax	Ultra TriLux	FUT48	6250K	T10		3350			$19 E		Pure White
Philips	Advantage	F40ADV	5000K	T12	24,000	3600	3250	82	$15 I		Creamy White
Philips	Daylight	F40D	6500K	T12					$4 C		Blueish
Philips	Daylight Delux	F40DX	6500K	T12	20,000	2325	2025	84	$4 C		Blueish
Philips	Ultralume	F40/50U	5000K	T12	20,000	3280	2950	85	$9 I		Yellowish
Sylvania /GTE	Cool White	F40/CW		T12					$1 J		Orangish

Notes:

• The Kelvin temperature is an approximation of the color tone of the light (the higher the bluer, the lower the redder). It is supposedly the color of light that a black body (a piece of metal) will radiate if heated to that temperature, but it's not very precise when applied to lamps other than incandescent. Noon time sunlight in the tropics is around 5000K. In the temporate zone, it's more toward 6000K. (See more on the Q&A page.)
• The CRI (Color Rendition Index) is an indication of how true the colors in the environment (your plants and fish) will look to your eyes under this light, with 100 being best (that of sunlight).
• The lumens rating reflects the brightness to your eyes. Some people have argued that this has little to do with the type of light that your plants need. However, recent studies seem to conclude that it does not matter much what kind of light you have, as long as you have enough for the plants. So lumens, CRI, and aesthetic considerations would probably be good factors for choosing your lamps.
• The spectrum of the GE SPX50 seems brighter than the indicated lumens. There may be two reasons for this: (1) this bulb is thinner, thus the light is more "concentrated" on its surface, and the spectrum is measured from a small spot on the surface of the bulb, and (2) I was overdriving the bulb by installing it on a 40W T12 electronic ballast.
• Sources:

  A.	GESupplyLight.com
  B.	HomeBase
  C.	HomeDepot
  E.	Leisure Time
  F.	That Fish Place
  G.	Pet Warehouse
  H.	Big Al's
  I.	Local light bulb stores
  J.	Generic, commonly available

• For information about the bulbs and ballasts I currently use, see my Tech page, and for my personal bulb recommendations, see my Notes and Q&A pages.