You'll want to remove and clean your bio filter before storing it inside for the winter. First, clean any filter media pads and bio balls located in your skimmer, waterfall box, pressurized filter, and/or in-pond filter. Filter media should be stored indoors for protection. If any of the media looks damaged or worn, start a list for items to be replaced during spring start-up.
When spring arrives and the water temperatures begin to approach 50 degrees, it's time to get things moving again. Your fish will be starting to move around and their metabolisms will become more active, so it's definitely time to get your biofilter active. Reassemble the filter with any new media, then hook it up and turn your pump back on. Your pond will probably have to go through a mini-cycle, so you may choose to add some beneficial bacteria to get things going as quickly as possible.
