I'd get a large rubbermaid and empty the entire tank before moving it.
That's what I did when upgrading from a 90 to 265 in the same spot; though in my case I needed 2 of the 150 gallon tubs (both of which I found used and flipped one of them afterwards). One for livestock and one for new water.
Depending on stock or customer, a 180 is going to be at least 400 lbs, maybe more. Took me and three additional equally husky chaps to carry in my 265.