You can reseal the tank.
Cut the silicone out, clean with alcohol and reseal with 100% silicone. I don't recommend a patch, I would replace the length of the seam. Just remember prep is everything. Silicone does not seal(bond) the cured silicone, this must be removed in the seam of the two panels. I use a razor blade(not utility) on a 45 degree angle and make several passes. Be careful not to go too deep(you just want clean glass edges to bond to), but enough to include the bottom panel in the new seal. Mask the two panels w/ tape and seal. Before the seal drys, remove the tape and you'll have clean, professional looking edges.
I personally have not had a tank leak but know its been done and my friend's tank hadn't leaked for 3 yrs before he sold it. I however have worked w/ silicone in construction for waterproofing the same technique is applied in remodeling, Baths, Windows, and Skylights especially.
If you decide not to try it let me know, I'll do it. I need the bigger tank and live in West Point. If you ever want to do some trading or compare notes, give me a shout.
ricknann96@verizon.net