You'll want to transfer a little filter media from your pond filter to give the bacteria a head start. (I assume you have a bio filter for your pond?) Otherwise you'll have to let the filter run with one tiny fish for a couple of weeks before there's enough bacteria growing in it to do a good job - ditto for storebought filters. All bio filters work on the same principle. You can buy bacteria to jump start your filter but I've never done that and don't know how well it works. All it needs is a little ammonia (fish waste, pee) to get started.

You should do some research so you understand filters, bacteria, pumps, ponds in general and how they work before you buy anything or put any expensive fish in it.