T8 vs T12 Lights
T12 and T8 refer to diameters of lamp tubes. Thus a T12 lamp has a diameter of twelve eighths of an inch, or 1-1/2 inches. Typically, a narrower lamp is more energy-efficient. Since the T8 is eight eighths of an inch, or one inch in diameter, it is a more energy-efficient lighting mechanism than the T12. T-8 lamps are available in a variety of lengths, and they also come in either straight or U-shaped lamps.
Fluorescent light bulbs also have an adverse affect on the environment. T8 and T12 lights are both created with mercury, a harmful element that can move into lakes, streams and estuaries once airborne. When mercury enters these bodies of water, it can affect the fish population, thus disrupting the health of the fish-eating food chain.