Having a protein skimmer in your outdoor fish pond is a must in order to provide optimum water conditions for healthy fish. They help maintain water clarity, remove harmful substances and increase the aeration of the water by removing organic compounds from the water such as algae before it decomposes. They also help remove larger debris before it can become lodged in the pond pump.
Cut a water inlet and outlet into the rigid plastic container. In the front of the plastic waste-paper basket, cut a large square hole. This can be accomplished by using a heat source to make the area you wish to cut out more flexible and then cutting away the plastic with a sharp knife. After the inlet is done, you must now cut an outlet hole in the rear of the container using the same method as cutting the inlet hole, however the size of the outlet hole should be commensurate with the size of your outlet tube. For example, if you normally run a water hose from the outlet of your pump into a waterfall, the hole in the rear of your plastic container should only be large enough to allow the water hose to pass through.
Place a submersible pond pump into the bottom of the plastic container. This should be done so that the end connected to the outlet tube is facing the rear. This automatically positions the front of the pump in line with the inlet hole. Thread the outlet tube through the outlet hole in the rear.
Place filter media into the container. The rest of the container should be filled with filter media up to the water line inside the skimmer. The idea is that no incoming water should be allowed to pass through the skimmer without coming into contact with the filter media. If you find that you have trouble keeping the filter media in place, add a colander or other removable plastic strainer over the media to keep it in place.
Hide the skimmer. In order to maintain the aesthetic appeal of your pond, hide your skimmer underground or under a floating decoration like a platform, but you must keep the pump under the surface of the water at all times in order for the skimmer to operate properly.