I use 4-foot 40-watt fluorescent tubes exclusively ... when I was told about the T5 lamps, I researched them very thoroughly ... I do not think the T5s lumen output justifies the MUCH higher price per lamp ... I still use T12s ... here is a great place to do your own research:http://www.1000bulbs.com/category.php?category=18
clicking on the details tabs, and comparing the T5 to the cheap T12, I think you may agree with my findings ... by the way, this link is a very good place to order your specialty bulbs, etc ... good luck ... :smokin: