Filtration foams

Filtration Foams, Double Mechanical and Biological Action

Filtration foams are essential in reef aquariums because they combine mechanical filtration (particle retention) and biological support (surface for colonizing nitrifying bacteria). Placed as the first step, they trap waste before it degrades into nutrients.

Their effectiveness depends especially on the pore density (PPI): a coarser foam allows better flow and clogs less quickly, while a finer foam retains more particles and requires more frequent cleaning. Some polyurethane foams around 20–30 PPI are also highly valued for their large useful surface area in biofiltration, provided they are not “sterilized” with each cleaning.

Historically, aquarists first used simple foams and perlon, then modern open-structure foams became popular due to their durability and versatility, in both freshwater and marine environments.