If you do not want to wait for weeks until the pond filter is working biologically again, you can help it along with filter bacteria. Then the filter will immediately run biologically again! It's very easy: moisten the filter material and sprinkle the entire contents of the tin onto it. Leave to react for 2 hours with the filter switched off. Done.
Product details with lots of FAQs and additional information can be found here: JBL FilterStart Pond .
Interesting facts about cleansing bacteria in your garden pond can be found in the JBL Themeworld Pond: Bacterias beneficiosas