call a windshield company and ask an see how much they would charge if they could come out and fill it. its kind of a weird idea but you never know worth a shot. also could look in to an aquarium repair company but they tend to be kind of expensive but they do warranty their work. if youre kind of a handy person look into replacing the piece of glass yourself. ive watched alot of youtube videos on how to build your own aquarium and it doesnt look like it would be very difficult.. i have a chipped aquarium but its at the top of the tank right by a seam and it hasnt gave me any problems but seeing as where yours is located id be worried. their is alot of pressure that far down in the tank.