Juwel Biocarb is a high-quality active charcoal sponge filter media designed for the Bioflow 3.0 Compact/H M filter system. Each package contains 2 replacement activated carbon sponges that help remove discoloration and harmful substances from aquarium water while maintaining optimal filtration. Key features: • Contains 2 active charcoal sponges • Compatible with Juwel Bioflow 3.0 Compact/H M filter systems • Removes water discoloration and harmful substances • Maintains effective mechanical and chemical filtration • Easy to install replacement filter media The Biocarb filter sponges are specifically sized for medium Juwel filter systems. The activated carbon helps absorb organic pollutants, medications, and tannins that can cause water discoloration. Regular replacement of these filter sponges (every 4-6 weeks recommended) helps maintain optimal water quality and clarity in your aquarium. The sponges should be rinsed before first use.