You must have done something wrong then IMO. I have one on my 55 gallon freshwater tank that's about 25 years old and looks brand new. The one on my current 20 gallon reef tank is about 5 years old and it looks fine too. How did you apply it? It's not rocket science. Just cut to size, make sure the back glass is clean, and then apply it with 4 pieces of scotch tape. Piece of cake. Sometimes you can wedge it up into the plastic frame, but I prefer to run some duct tape all along the top edge to seal it shut.