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Hi all,

I have seen all these threads containing "T" lighting, and i am wondering what this means, and the difference it makes in aquariums and plants.

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The T # is reference to the diameter of the fluorescent tube.

T12 is 1 1/2"
T9 is 1 1/8"
T8 is 1"
T5 is 5/8"

The T12 is the most common ie "the shop light" and is the least expensive.For aquariums the critical info is the color temp., and the wattage.

Thanks! I just heard that the smaller the "T" the smaller the wattage used, but same light output. Thats perfect for light cost!

I guess i need a special light stripfor them.......

Thanx again!

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Just an addition, the number followed by the T is the diameter of the bulb in 1/8's of an inch. As stated before, T-12 is 12 eigths of an inch, and therefore 1.5 inches round.

You need a different ballast to run different bulbs. Occasionally you can fudge a little and run something around T8-T12 in the same fixture but most of the time it doesn't work out so well. After a bunch of flickering I blew the ballast trying to run T12s in a fixture designed for T8s or T10s(I don't remember exactly). Unless your dealing with something special like HO or VHO fixtures it usually isn't an issue since nearly all aquarium fixtures use the same bulb size and nearly all bulbs sold are that size. It's when you start mixing and matching that you run into trouble. For my mistake I was using cheap fixtures designed for growing potted plants with bulbs sold for standard aquarium fixtures and they turned out to be a different size/rating.