I tryed UNSUCSESSFULLY to reseal my 125 last year.But my problem was in the retaining ring around the top of the tank.It was broken at the leaking corner.But if yours is OK,You MUST remove ALL the silicone from this joint.Then apply a generous ammount of new silicone to the seam from the inside.Making sure the sealant ozzes all the way through,and comes out the seam at the outside of the tank.Then you need to clamp the corner till it dries.This can be done with a couple(two or three) woodworking "bar clamps". Don't clamp it too tightly.That will only push all the sealant out of your seam.There should be about 1/16" of space between the panes of glass.This space is of corse filled with silicone.Once you have it clamped,you can smooth off/remove the excess with a WET FINGER on the inside. The outside is easier to cleanup if you let it dry,then carefully cut the excess off flush with the glass using a razor blade....GOOD LUCK...