The fine blue filter sponges in a Juwel filter house important bio - cultures, which are responsible to effectively clean the water. You should clean or replace one sponge at a time every 9 - 12 months to maintain the right biological balance in your aquarium.
Contents 1 sponge.
Check Juwels compatibility chart to see which filter media you require.
See how frequently Juwel recommend replacing this filter media.