The Fluval AquaClear BioMax is the biological media insert for the AquaClear 50 (AC50) power filter. Its porous ceramic rings pack an enormous amount of surface area into a small space, giving beneficial bacteria a place to colonize and keep the nitrogen cycle running. Strong biological filtration converts toxic ammonia and nitrite into far less harmful nitrate, so your fish stay healthy. It works in both freshwater and saltwater aquariums. Formerly sold as AquaClear BioMax. Pair it with BioFoam for mechanical filtration and Activated Carbon for water polishing, or refresh everything at once with the AC50 Filter Media Kit. Browse all inserts in our Filter Media & Cartridges collection. Features Porous ceramic rings offer a huge surface area for beneficial bacteria Supports a healthy nitrogen cycle: ammonia to nitrite to nitrate Long-lasting biological media, rinse and reuse for many months Custom-cut insert drops straight into the AquaClear 50 / Fluval AC50 media basket Works in freshwater and saltwater aquariums How to Use Rinse the BioMax gently in used aquarium water, then set it in the top of the AquaClear media basket so the beneficial bacteria stay fed with oxygen-rich water. Never rinse it under tap water, since chlorine kills the bacteria colony. BioMax lasts a long time; replace it only when the rings start to crumble, and avoid changing all of your biological media at the same time so the tank does not go through a mini-cycle. Specifications Product AquaClear BioMax AC50 (formerly AquaClear BioMax) Media Porous ceramic rings (biological filtration) Fits AquaClear 50 / Fluval AC50 hang-on-back filter (20 to 50 gallon) Supports Beneficial bacteria and the nitrogen cycle Net weight 2.8 oz (80 g) Water type Freshwater and saltwater Brand Fluval Recommended Pairings AquaClear / Fluval AC50 power filter, the filter this insert fits AquaClear AC50 BioFoam for mechanical and biological filtration AquaClear AC50 Activated Carbon for chemical filtration AC50 Filter Media Kit, which bundles BioFoam, carbon, and BioMax FAQ Which filter does this fit? The AquaClear 50 (also sold as the Fluval AC50), rated for 20 to 50 gallon aquariums. How often should I replace it? BioMax lasts a long time. Rinse it in tank water at cleanings and replace it only when the rings begin to break down. Can I use it in saltwater? Yes. The ceramic media supports beneficial bacteria in freshwater and marine tanks alike. Should I swap all my biomedia at once? No. Replace it in stages so your tank always keeps some established biological media and avoids a mini-cycle.