This biological filtration is usually supplemented by protein skimmers.

However, it does require a fairly large aquarium, with the usual neotropical cichlid requirements of good biological filtration and sound husbandry.

Foam media is also supplied in some units as the main source of biological filtration.

Because the numerous particles have a high surface area, substrates are often employed in biological filtration.

This includes mechanical, chemical, and especially biological filtration.

Materials with a greater surface area provide both mechanical and biological filtration.

Some filter materials, such as plastic "bioballs", are best used for biological filtration.

It passes through a sponge where mechanical and biological filtration takes place, and is then passed back onto the water.

The next chamber or chambers generally hold the main media, aimed at biological filtration.

The sewage works was built in the mid 1960s and secondary treatment is by biological filtration to the Royal Commission standard.