I would also pay attention to WHERE you store the tank. Keeping it off the ground or off the basement floor will help, and if it's in a heated room that would be much better as far as keeping moisture out.
You might even consider buying one of those heated rods (golden rod) that they use in safes to keep them dry and hang it inside the tank. They are pretty cheap at Cabellas, etc.
New Port Richey,Fl