Guys, I ran my tank (29g) under VHO's for a long long time and last year upgraded to T5's, and I'm VERY happy with the results. I used the same ballasts and endcaps (just have to make sure your ballasts are rated for the right bulbs)--and the color is better, there is more light in the same amount of space, they run cooler... If you are looking to upgrade, or to switch to VHO from something else, I'd highly recommend the T5's.