Fluval BioMax Biological Filter Media, 500 g

Fluval BioMax is biological filter media: porous ceramic rings that give beneficial bacteria a place to live. Those bacteria convert toxic ammonia and nitrite into less harmful nitrate. More surface area means a bigger, steadier bacterial colony. This 500 gram pack fills a basket in most canisters.

Which filters it fits

Fluval lists it for the 106, 206, 306, 406, FX5, FX6 and older canister series. The rings also work in the Fluval 307, the FX6 and almost any filter with a basket or tray, including sumps.

How to load it

• Put mechanical foam first, so debris doesn’t clog the ring pores.
• Fill the bio basket loosely. Packed too tight, water flows around the rings, not through them.
• Rinse new rings in dechlorinated water to clear dust.

Replacing it safely

Fluval suggests replacing it monthly for best results, but only half at a time. Swapping all the bio media at once removes most of your bacteria and can cause an ammonia spike. Many keepers stretch that interval much longer, swapping half only when the rings start to crumble or stay clogged after a rinse.

Cleaning

When you service the filter, swish the rings gently in tank water you’ve just removed. Don’t scrub them or rinse them in tap water.

Freshwater or salt

BioMax works in both freshwater and marine systems, and the rings don’t break down or alter water chemistry under normal use. Because they last, a single pack can serve as the core of your biofilter for a long time. In a new tank, pair it with a bacteria starter like Seachem Stability to help the colony get going.