Or until someone whacks it with a lump hammer.LS-X is basically a neutral silicon sealant and dries very similar to the stuff you use around the bath and window frames! Once set if it's not leaking within 24 hours then it will last for pretty much forever. It can easily deal with small gaps like that. Should be good for the life of the tank.
Or that... lol....Or until someone whacks it with a lump hammer.