External Media

Media for canister filters, meaning the foams, cartridges and granular products that go inside a sealed external unit. The range here is largely Fluval: BioMax ceramic rings, foam blocks, carbon, ClearMax and Quick-Clear polishing pads.

Three jobs, three stages

• Mechanical: foam and polishing pads trap particles, and are rinsed or replaced most often.
• Biological: porous ceramic media house the bacteria that process ammonia and nitrite. Replace these sparingly, never all at once.
• Chemical: carbon and resins pull out tannins, medications and dissolved compounds.

Fit is the other variable, as media is cut for specific canister models.

Seals, impellers and hosing live in Replacement Parts.