Resealing tank

[sphelps]

Silicone will stick to cured silicone provided it's clean. This is strange myth which makes little sense. When building larger tanks with thicker glass it's actually best to do the seams in two steps to ensure it silicone cures throughout the seam.

The confusion must relate to the old silicone being contaminated or covered in algae and of course the silicone itself can be difficult to clean. So on the safe side it might be best not to rely on such a bond but realistically if you clean it, it'll be fine. You can use alcohol to clean the old silicone in the area where the new will overlap.

If you don't agree or just unsure, try an experiment. Simply make a "goop" of silicone and let it cure, next apply some more to make another "goop" that attaches to it. Let that cure and see how strong the bond is.

If it's really true that silicone won't stick to silicone (even sounds ridiculous) then you should never reseal a tank in the first place. This is because you can't remove all the silicone in a reliable way from the glass unless you use an actual chemical to remove it which you don't want to use unless you completely dismantle the tank.