If your pump has a pre-filter, clean or replace it. Many pumps have easy access to the impeller. If you did not clean the impeller in fall, be sure that you do so now. String algae or small stones can cause serious damage to a pump. If your pump is more than a few years old consider replacing it with a more energy efficient one. In some cases it will pay for itself in a few months. Pond pumps and filters come in both submerged and in line (out of pond). We recommend a pond pump that is large enough to exchange all of the water in your pond hourly.