I did a little research on my light situation - interesting:
> The 'T' stands for tube.
> Tube diameter is measured in eights of an inch
> T-5 = 5/8" of an inch
> T-8 = 1" (8/8 = 1)
> T-12 = 12/8 or 1.5"
> T-8s can be either fluorescent or LED.
> My setup has full spectrum LED T-8s.