you could get condensation on a tank kept at 65°F, but how much depends mainly on the room’s temperature and relative humidity.

For example, in a typical house at 75°F:

• 40% humidity: probably no condensation.
• 50% humidity: probably little to none.
• 60% humidity: you’re getting close to the dew point.
• 70% humidity: yes, the 65°F glass is likely to sweat.

In humid Georgia, especially in summer, I’d expect at least occasional condensation on a 65°F lobster tank—particularly if the room is warmer or humid outdoor air gets inside. It may be more noticeable around the chiller plumbing and hoses, because those surfaces can be colder than the tank glass itself.

At 65°F, though, I wouldn’t expect the aquarium to constantly drip like a glass of iced tea. If you dropped it to 55–60°F, condensation would become a considerably bigger issue.

For your lobster setup, 65°F strikes me as a pretty nice compromise: cool enough to be much more lobster-friendly while not turning the aquarium into a giant sweating refrigerator.