Aquarium filter media is a broad term used to classify materials used for aquarium filtration. Filter media removes pollutants, odors and discolorations from aquarium water to create a cleaner, healthier environment for fish, corals, inverts and plants.
Fish tank filter media is usually categorized into three basic types: mechanical media (traps detritus), biological media (provides a surface for bacteria to colonize on to help break down waste such as ammonia and nitrite) and chemical media (absorbs organics from the water).
Mechanical media includes items like filter socks and filter pads. Mechanical filter media traps floating debris like fish waste or excess food as water passes through them. Many feature micron ratings to help you shop: a higher micron rating means the pore sizes are larger while a lower micron-rated media will feature smaller pore sizes. Mechanical filter media should be cleaned or replaced every 1-4 weeks.
Biological filter media includes bio balls, biopellets and ceramic resins. Biofilter media provides ample surface area for beneficial bacteria to grow which helps naturally break down aquarium waste. Bio balls and ceramic fish filter media do not usually need to be replaced but should be rinsed occasionally. Biopellets, which help reduce nitrate and phosphate, do need to be replenished as they eventually break down in the waste removal process.
Chemical filter media includes carbon filter media, phosphate removers (like GFO filter media), nitrate filter media and ion exchange resins. These types of saltwater filter media help reduce and remove organics that cause smelly, yellow water and problematic algae caused by phosphate and/or nitrate. Chemical media works by absorbing or adsorbing different organics/chemicals from water which helps hobbyists to maintain ideal reef tank parameters for livestock.
Successful aquarium owners generally opt for a combination of all three types of aquarium filter media to achieve the highest quality water possible. We are happy to make specific recommendations for your freshwater, saltwater or reef tank—contact us and our experts will be happy to share their knowledge with you!