Contrary to an earlier post, UV filters can absolutely eliminate parisites. The amount and type of filtration/ sterilization you get from your UV filter is solely dependent on the flow rate. The slower the flow, the more you get out of your UV. for this reason its better to go with a stand alone unit rather than a canister with a built in UV. most stand alone units will have a chart of flow rates for different levels of filtration.
IME you can't go wrong with a Turbo Twist. They can be a bit pricey, but absolutely worth the money.