Fluval Pre-Filter Media Ceramic Rings

Fluval Pre-Filter Media is a 750 g pack of solid ceramic rings for the first stage of a filter. Unlike porous bio rings, these are made to trap large and medium solid particles and spread the flow evenly. That keeps finer media further along from clogging.

What a pre-filter stage does

When water first enters a canister it carries the most debris. Without a coarse stage, that debris lands on sponges and bio media and clogs them fast. Pre-filter rings take the brunt of it, so the rest of the filter stays clear for longer and you replace fine media less often.

Where to place them

• In the bottom tray of a canister, where water enters.
• Before foam and floss stages.
• In the first chamber of a sump.

In Fluval canisters like the Fluval 207 or FX2, they go in the lowest basket.

Cleaning

Rinse the rings in a bucket of tank water when you service the filter. They’re solid ceramic, so they don’t wear out the way foam does, and they can be reused for years.

Fresh and salt

Fluval lists the rings for medium and coarse filtration in freshwater and saltwater aquariums.

Pairing

Follow the rings with a sponge, then a fine floss or polishing pad, then bio media such as Fluval BioMax. That order moves from coarse to fine and keeps each stage working at its best.

The rings are heavy and dense, so they also help keep lighter media from floating or shifting in the tray. Fill the basket loosely so water can move between them, and avoid overfilling, which stops the basket lid from seating properly.

Do you need them?

If your canister clogs quickly or flow drops between cleanings, adding a coarse first stage is often the simplest fix. Hang-on filters with small baskets usually rely on the sponge instead.