90 Gallon leaking..

[Black Phantom]

Which part of the tank had the leak. I'm assuming the top as you said it didn't leak until full.
The only way in my book to properly fix a leak is to drain the tank, let it fully dry, remove most of the old silicone and reseal the joints.
How old is the tank? If it's more then five years old I might look to a Christmas sale or another reefer with a good tank.