Just saw your post and wanted to let you know I had the same type of problem with a stealth(if you mean Marineland), it didn't shut down when it was out of the water and ended up rupturing and boiling off in my tank for an unknown period of time. Fortunately my tank is grounded and its didn't effect any of the tanks inhabitants. Made my apartment smell like you would not believe though. Anyway, I email Marineland right away and they have actually put a "stop sale" on the because they have been found to be defective. You may want to contact them and see what they can do for you. The are sending my a Visitherm to replace it for free, so they might help you out in some way.