I haven't heard about this, but on all 3 of my ten gallons, I have the led light almost right on the glass top. They have handles on each end, so they are about a half an inch right above the glass, and I haven't had any problems. I leave it on the day lights 10 hours, then on the Blue night lights 6 hours, and 8 hours off at night. But I have only had them this way for about 4 months.