You're probably going to have to buy a separate external pump and Bead/Sand Filter or a series of large canisters like Ocean Clears plumbed inline in order to adequately filter a 1300g pond with canisters. It would be cheaper just to build a huge rubbermaid sump filled with scrubbies and such, though in the end if you want quality filtration on such large body of water it won't really be "cheap".