Measuring Light bulbs

[tmcgee]

Hey just a quick question. I measured my bulb today for my 10 gallon all glass setup. Well i dunno if i am supposed to round up or what but it only measured barely over 17 inches from pin to pin. I would assume it is the 18" model but I would like confirmation before I order one online and it ends up being wrong. TIA

 

[tmcgee]

And I was thinking about getting Coralife Colormax bulbs for freshwater aquariums. Anyone use these at all?? I am under the impression they bring out the color in the fish a little more.