So I bought a used tank from discount aquariums and just to setting it up. Come to find out that there is a really slow leak coming from the top right corner trim. I immediately lowered water level about 6in and put some silicone on there, I was kind of rushing during the whole process cuz I was leaving town the next morning. Well fast forward a week and I still have a very very slow leak... Ideas?thoughts? Best silicone to use?