Stefano, In the photo the T-8 seem brighter but the T-5 HO with the polished reflector is the brightest.I also have one blooming bulb which has more of a redish tint than a blue/white color. I think that the lack of the reflector on the T-8 makes them look brighter. The other T-5's needed a bulb replacement.I just did do that.I will need to post another pic. As far as heat, the all seem close to being the same. I do not detect any really hot conditions. I have a temp. gauge on the middle shelf just above the 4 T-5 bulbs (82 /F 27.8/ C) I hope this helps Rich