Reseal the whole tank, not just an area. Use a razor blade and remove all silicone. Rub and clean with alcohol. Then tape off area and apply silicone. Its pretty easy to get the silicone out. Just time consuming.
I remove tape immediately after finishing applying the silicone. If it skims over it will give zagged edges.
If you get some in areas you don’t want it easily removed with paper towel and alcohol. That big of tank when you finish applying silicone , start removing tape where you started applying first.