Originally Posted by rcoultas
I hate to rain on your parade but ....
All good intentions aside - technically you were both incorrect with your answers.
HO light is a measure of the output of the ballast - an HO ballast fire the lamps with an 800Ma output. It has nothing to do with the output of the lamp although they are generally brighter
T5 is a measure of the diameter of the fluorescent lamp - these are fire normally by an electronic ballast with a 425Ma output.
Which is better? IMO the T5 are, overall, the better value. HO's use more electricity, generate far more heat, and have a shorter lumen maintenance period.
The T5's are a bit lower on the lumen output but they use less energy, run cooler, and have an exceptional lumen maintenance.
Lumen maintenance is how well the lamp performs over it's lifetime and how it maintains it's level of light output over that same time. The HO's chart shows that the dropoff is almost immediate and then maintains the T5's have a very slight decrease and very slight decline rate.
HTH
Manufacturers rate their lamps as standard wattage, very high output, normal output, etc. Of course the ballast is rated the same way, but there is a difference in the design wattage of the lamp, and the industry generally refers to the various standard wattages in terms described above.
In 48" lengths, T5 lamps...
Normal Output is something like 20w (I'm not sure of the exact wattage)
High Output is 54w
Very High Output is 85w.