Biofilters

Biofiltration in aquaculture is a key process in managing water quality, especially in recirculating aquaculture systems (RAS). It allows for the removal of nitrogenous waste produced by fish, particularly toxic ammonia, by biologically converting it into less harmful compounds (nitrates).
Definition of Biofiltration
Biofiltration is a natural process that uses nitrifying bacteria to transform ammonia (NH₃), excreted by fish, into nitrites (NO₂⁻), and then into nitrates (NO₃⁻), which are much less toxic. This process is known as nitrification.
Steps of Nitrification:
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Ammonia (NH₃/NH₄⁺) → Nitrites (NO₂⁻)
Carried out by bacteria of the genus Nitrosomonas. -
Nitrites (NO₂⁻) → Nitrates (NO₃⁻)
Carried out by bacteria of the genus Nitrobacter or Nitrospira.
How Does a Biofilter Work?
A biofilter is typically made up of a medium (such as plastic beads, foam, sand, or ceramic) that offers a large surface area for bacterial colonization. Water passes through this medium, allowing the bacteria to process nitrogenous compounds.
Advantages of Biofiltration:
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Controls toxic compounds (ammonia and nitrites)
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Maintains water quality
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Reduces the need for water changes
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Provides a stable environment for fish
Integration into Aquaculture Systems:
Biofiltration is essential in:
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Aquaponic systems
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Closed or recirculating systems
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Intensive pond farming
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Systems sensitive to water quality (fry rearing, nurseries, hatcheries)
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Aquariums
AQUACULTURE France designs, sizes, and manufactures a full range of biofilters adapted to all needs (gravity-fed or pressurized systems).