Hi Jenn,
It all has a lot to do with how big your pond is, how big the pre-filter is,, how many fish, how many plants.
My pre-filter is skimmer type PVC pipe attached to the side of my plastic pond that flows into a resevor where the pre-filter catches most of the big goo. From there the water pump sends the water inline to the UV clearifier, and then in to the boi-filter. That water returns to the pond via the base of my water fall. You can view my disorderly pictures that are noted at my signiture.
I'm sure that someone here will be able to help you with your question.