Your water feature's pond pump filter is the most important part of the overall pond. The design, plants, rocks, and even fish can add some great attractive qualities, but no functional purpose. The pond pump and filter move the water and keep it clean.
Step 1 - Choose the Right Size
Often times, people building a pond in their backyard choose the wrong size pump for their needs. Pumps have a large job that can overwhelm a pump that is too small. A pond pump filter needs to be able to circulate water through a screen-type filter to another filtration tank outside of the pond itself. Then the water is returned through another pipe, usually ending up in a waterfall feature. Most pumps, even ones that are packaged with a pond kit, cannot adequately handle the correct rate that the water must be "changed."
Changing the water refers to circulating the entire capacity of the pond through the filtration device, thus cleaning the entire pond. However, with biological debris and other debris blown in by wind, the pump does not just have to push along water. A typical "change" rate should at least four to five times an hour. If your pump does not do that, then you should look into larger pumps.
Step 2 - Construct Filter Box
Your filter is not going to go into the water, so it must be placed in some sort of attractive container or a constructed box. You can hide this with plants or rocks if you choose. This container then goes to the side of the pond, on the farthest end from where you will place the pump.
Connect the wire to the electrical box by running wires, through a plastic PVC conduit underground, from the filter to the electrical supply. Using hose clamps you can connect both the inlet hose and the outlet hose, putting both in places where they are going to be hidden from sight.
Step 3 - Install Pump
Run water into the pond until the bottom is covered. This will help you get rid of wrinkles in the liner and show you any low spots. After filling in these spots, and fixing liner, you can place the pump on the bottom of the pond. Your pond pump filter can either be set out freely, or put into a water safe container for aesthetic purposes.
Connect the hoses to the pump to send water to the filter, and begin filling the rest of the pond. After the water is finished filling, plug in the pump, and check to see if the water is running freely (without any clogging or suction noises).
Step 4 - Add Plants and Fish
The major attraction to any pond is not the pond pump filter. It is the plants and fish that you put into it. Let the pump circulate the water for a few days to get rid of any debris from construction and to check the "change" rate. Once everything is set on the pump and the pool, add your biological elements and enjoy.