hmmm, I have not had a heat issue with them, and because I have a 30 gallon hex, nothing fit inside the canopy, that was the only way to go for PC's, I have been satisfied.

You do hav to remember however, that the ballasts are onboard with these lights, so yeah, they are going to generate heat. If it's the only thing you can fit though... oh, and the heat is no where as bad as a MH, and a simple fan on the canopy will whip it away.