Your pond filter and pump are truly the heart of your pond. Clean them thoroughly early in spring, when water temperatures are between 40° and 55°F. Waiting longer could disrupt the beneficial bacteria trying to repopulate after a winter freeze.
Remove all media from the filter and rinse the filter container. Make sure the wastewater is not running into the pond. If you need to get in your pond to retrieve your filter, you'll want to wear waders, as water this cold is quite uncomfortable.
All filter pads, sponges and bio media need to be thoroughly rinsed. Do not allow the bio media to dry out, or let it come in contact with chlorinated water during this process. Gravel or lava rock type bio media should be replaced every three years. Plastic media does not need to be replaced if you are able to rinse it free of debris. If any pads or sponges are too dirty to return to their original color, they should be replaced.
Magnetic drive pump
Don't forget the pump! Check the manufacturer's recommendations for cleaning. Magnetic drive pumps should have the impeller cleaned (not scrubbed) as well as the impeller chamber (the cavity the magnet rests in).
Reassemble the filter and start it up. Check for leaks and proper flow rate. Then you will want to dose the pond with bacterial additives to replace those lost over the winter. Be sure to check directions as to water temperature requirements and how long to wait between treatments.
Article by: Veterinary & Aquatic Services Department, Drs. Foster & Smith