You can "attempt" to fix it, but you'll never (at least I wouldn't) have piece of mind the tank will last. On a ten gallon tank, it's much easier just to buy a new tank as the cost is minimal. If you decide to, heres some info I pulled off the net (thanks to the original poster):
Repairing Cracks
For repairing cracks you will need glass (in most cases) and probably a glass cutter. The majority of cracks will be on the bottom of the tank, unless they were caused by a blow (falling rockwork).
An aquarium stand that has a high spot or is not steady may cause the aquarium to twist, and the bottom panel to crack. My stands and racks are wooden, and I use a sheet of styrofoam between each stand and tank. This helps alleviate any high spots and some of the twisting.
If the crack is a small one near a corner it will probably be an easy fix. Drain, clean and dry the tank, getting all the moisture out of the crack. A hair dryer is good for this. A heat paint stripper would work, but the high heat could damage the trim or even cause further cracking of the tank. You will probably want to remove the trim anyway. It's only held on by silicone. As discussed earlier, if you have one of those tanks with the outer panel set down into a groove on the bottom trim instead of on the bottom panel, it is almost impossible to remove the trim.
To repair the crack, just run a bead of silicone along the crack on both sides. In most cases this will work, but it is not pretty. A long crack can normally be fixed using a band-aid method. Again, the result is not pretty, but if the crack is on the bottom or the back, it can be hidden.
The best method for repairing a crack is to use two pieces of glass that are a little longer than the crack, placed so they overlap both ends of the crack or as close to the edges of the tank as you can get. You can often get away with one piece on the inside if you find it difficult to use a piece on the outside bottom. Sometimes the bottom trim is such that the tank would end up sitting on the band-aid glass. The result would be a completely broken bottom!
Cutting glass is not difficult, but it gets easier with practice. Use a straight edge as a guide for the glass cutter. Place the straight edge along the intended cut line, ensuring that the cutting tip is exactly where you want it. Unlike wood, you cannot cut just a little more away. Hold the straight edge firmly and run the cutter the full length of the glass in one stroke. Overlapping lines will almost always result in a broken piece of glass. Do not press too hard, but use enough pressure to ensure a clear etch. Many of the pros dip their cutters in a mixture of kerosene and oil, but not too many of us hobbyists have that kind of stuff sitting around.
Put the glass over the edge of a table or a piece of wood and press down sharply at the scribe mark. If done correctly, the glass will snap right along the mark. You may wish to practice first on scrap glass. Remember, cutting really narrow strips is almost impossible for an amateur, and difficult even for the professional. It would be wise to wear eye protection and heavy gloves.
A tip here: buy a top-quality glass cutter. The cheap hardware store ones just will not cut it (bad pun intended). You might want to get your local glass company or hardware store to do the cutting for you. They will charge, but if you can watch you will get the idea. This is one place where seeing it done is far better than the written word.
If the glass is thicker than 3/8-inch you may have to do a bit of searching to find someone to cut it. This is thicker glass than hardware stores and many window stores are prepared to cut.
Clean all new glass with white vinegar or acetone. New glass is shipped with an oil coating to protect it. The silicone will not adhere to the glass properly if this film is not removed.
Old or salvage glass tends to be brittle, and if scratched will often break at the scratch rather than along your mark. Salvage glass often has a buildup of dirt or chemicals that requires cleaning before you can properly scribe it. Again, acetone is the cleaner of choice.
Back to the repair. Run a bead of silicone along the crack. Then run a bead near the edges of the band aid glass and criss-cross along the length. Place the glass patch over the crack and press into place. Make sure you have a seal on all sides by running a bead along all edges of the band-aid. Repeat on the other side. This is not pretty, but it works.
