Just thought Id share. I bought two 250 watt Marineland stealth heaters about two months ago. After about a week I was sitting in the room and would hear this high pitch noise every couple of minutes. After looking around for quite a while I looked in my tank to see steam coming out of one of the heaters. I removed the heater and and exchanged it at Petsmart with not questions asked. After another month I was cleaning around the tank and smelled something burning. Well I looked right towards the heaters and gues what? both had steam and one of the cases was actually starting to burst. Just thought Id let you know as the end results could have been horrible,