A pool pump, and filter assembly, should be sized according to the volume of water that you have in your pool. This water should be turned over approximately every 5 hours. It will need around 7 complete turnover periods though for all of the water to actually pass through the filtration system.
The pool pumps that we currently supply are manufactured by Pentair, normally the Ultra Flow model. They are guaranteed for 3 years and have particualrly good power/performance figures. The table below shows these performance figures as well as the costs of these pumps.