There is a lot of confusion regarding fluorescent tubes in the reptile keeping world regarding T5 and T8. So what is the difference?

The original out of the two, is the T8 tube. They have been traditionally known as a 1 inch diameter tube. They have been available for a couple of decades in three “grades” for reptile use;

  • 2% or full spectrum – very low UVB output, but gives a similar colour spectrum to natural sunlight.
  • 5-6% or rainforest power, ideal UVB tube for species that require UVB, but at a lower level, often found where forest species live.
  • 10-12% or desert power, ideal for species requiring higher levels of UVB, for species that bask in intense levels of sun.

The method of use is to pick a UVB output for the species you are keeping, this may mean a visit to your local specialist to ascertain the habitat the species you are keeping originates from. Some examples; species such as Water Dragons, Day Geckos and similar are suited to 5-6% – species such as Bearded Dragons, Bosc Monitors are suited to 10-12%. T8 tubes however give a very limited colour output, this can be seen with the blue tinge. They are supposed to be complimented with a 2% or full spectrum tube to balance the colour spectrum. This will give a psychological well being to any species and they will generally be happier and eat better. For each 5-12% UVB T8 tube, there should also be a T8 2% tube provided. There would need to be two controllers and fittings, or a double controller.

The newcomer, with more recent technology, the T5 fluorescent tube is a much smaller diameter at 5/8 inch diameter. The T8 and T5 tubes are not compatible, not only are they a different size, the electronic controllers both tubes require to work are specific to the tube, a T5 controller will only “fire” a T5 tube, and a T8 controller only a T8 tube. Unlike T8 tubes, T5 fluorescent tubes are not available in 2% full spectrum grade, this is because T5 has the full spectrum element built into the one tube – when using a T5 UVB tube there is no blue tinge. One controller is required. The luminance of a T5, that is the “brightness”, is far greater in a T5 tube in comparison to a T8.

Pros of T8;

  • Cheaper than T5 per tube, and per controller

Pros of T5;

  • Better quality of light
  • Only requires one controller, neater fittings.
  • Gives a longer lived UVB output.
  • There is a high output 14% version, very suitable for uromastyx and similar.


 It may seem cheaper to provide a T8 fluorescent tube for UVB provision, but there are some downsides to this thought process. The T8 typical only gives a usable UVB output for around six months, a T5 will give a much longer and stable output of around twelve months. This means a T5 tube, over the twelve month period will be cheaper.

The luminance levels from a single T5 tube is far superior than any form of a T8 tube, they are much “brighter”. A T5 tube will provide as close as possible luminance level to the sun, at this current time, out of all the fluorescent tubes. Not only is the purchase of a T5 tube better on the pocket, its also better for your UVB loving animals.

The T5 tube is a clear winner, yet the T8 is still the best selling tube. It’s time for a rethink.







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