I wouldn't remove the trim... I had an AGA leak on me, heres what I did:
get inside the tank with a razor: strip out ALL of the bottom silicone, and up the sides until where the plastic covers. then, re-silicone A BIT FAT LAYER all over it: its going to be covered up by sand anyways, and the farther the seal goes out on the sides, the less likely its going to leak. the thicker the seal, the longer it'll last before becoming brittle.
and make the corners really thick. it takes awhile to do... on a 35 hex it took me about 2 hours. AND make sure you do it in a well ventilated area when you get to siliconing it!!!!