I was going through my weekly cleaning on our 75g tank the night before last and discovered a 3-4 inch crack on the outside of the glass. It's on the front pane an inch or two from the bottom and starts from the corner seal and spreads towards the middle. I felt the inside of the tank it it doesn't seem to go all the way through the glass. Can I repair this with sealant! I'm nervous that it's going to start leaking and destroy our floor! Help!