Kidding kidding. Its difficult to patch a leak from the outside, as the pressure will keep blowing it outwards. the strength from a silicone seam is enforced by the fact that the water pressure is "pushing" it to the joint.
The only way I know how to properly fix it is to drain and re-silicone. and that's a PITA because silicone doesn't stick to itself. You'll need a LOT of overlap and depending on your gravel line - might be ugly.
Others may have better idea's though!
Might be the perfect time to justify a bigger tank ?