sprung a leak

HI I just aquired a used 50 gallon tank for free from a "friend" it was sitting empty in his living room for well over 5 years once i got it home upon further inspection i noticed some of the silicone had come undone so i proceeded to cut out where it was falling off and noticed all kinds of "mud" behind it figured it had been leaking for awhile so i siliconed itafter cleaning all old yucky stuff out. it is one of those tanks that has a chrome frame around it. anyway i waited 48 hours put it in my house where i wanted it with a few sheets of clean dry newspaper and started to fill it

low and behold im still leaking im draining it now do i have to redo all of it or just corner where the leak is?

any pointers on how to do this? please let me know

thank you in advance

Danielle Oscramommie