T8
From The Aquarium Wiki
T8 refers to those types of straight aquarium fluorescent lighting tubes which are eight - eighths of an inch (2.54 cm) in diameter and use a G13 bipin socket.
These tubes are typically being replaced by more efficient and brighter tubes like the T5.
- You require a specific ballast unit to drive T8 tubes. You can not use a T5 ballast.
- Metric version is called T26