Running 3 stealths right now (two 250's on my 150-gallon) and a single 250 on a 22-gallon, never had problems with them.
I have used a single 250-watt on a 45-gallon tank for almost 4-years before tearing the tank down.
I really miss the light on the heaters for some piece of mind, the only reason I have considered Jagers vers Stealths is for the light and quality.
I hear there NOT FULLY submersible so that keeps me away from them.
I always keep all my tanks filled ALL the way, not to hijack the thread, but is this true?? What is the deal with this?