FYI, I made an assumption that the OP was referring to an aluminum tank... But, Gulf, you're right - he didn't say what he has. Plastic is of less concern and Al.
For me once it's 20 years old brand new tank/tanks epoxy coated. New hoses new hose clamps and the smallest most over looked and very very important is the gasket on the cap. I read about that one in a magazine !Would love to hear thoughts and experiences.