Bulb fixture differences?

Could someone explain to me what are the differences between a reptisun t5 tube light versus reptisun t8 tube light?

Which UVB light should I use?
The best UVB light is a ReptiSun 10.0 fluorescent tube HO (Or Arcardia 12% in the UK). Compact or coil bulbs do not emit the proper amount of UVB light for a bearded dragon, and should not be used. Other brands, such as the Zilla Desert Series and ReptiGlo have been known to cause eye problems and other health issues with bearded dragons, and should be avoided. The reason that some UVB lights (Zilla, ReptiGlo, coils/compacts, ect.) are considered dangerous is because the wavelength of UVB that they emit is shorter and more intense than the wavelength of the "safe" lights (ReptiSun, Arcadia).
UVB lights should be replaced every 6 months. The T5’s are a strong bulb and only need to be replaced once a year – the T 8 every 6 months--- where as the T 8 are not as strong—they need to be placed inside the tank the T 5 10.0 bulb approx 10-11 inches from basking spot – the T 8 approx 6-8 inches from basking spot—the cover needs to be off the bulb for full effect of the UVB rays--
Karrie

Hello,

Thanks for the explanation, Karrie.
Very true, the T5 tubes are newer models than the T8 tubes are. The UVB to UVI ratios are
much better with a higher quality of UVB as well.

Tracie